,,geological ,,contemporaneity ,,and    
,,persistent ,,types ,,of ,,life4  ,by  
,thomas ,h4 ,huxley  #a    ,,merchants  
occasionally go through a wholesome1    
though troublesome and not always       
satisfactory1 process which they term   
taking stock4 ,after all the excitement 
of speculation1 the pleasure of gain1   
and the pain of loss1 the trader makes  
up his mind to face facts and to learn  
the exact quantity and quality of his   
solid and reliable possessions4  ,the   
man of science does well sometimes to   
imitate this procedure2 and1 forgetting 
for the time the importance of his own  
small winnings1 to re-examine the common
 stock in trade1 so that he may make    
sure how far the stock of bullion in the
 cellar--on the faith of whose existence
 so much paper has been circulating--is 
really the solid gold of truth4  ,the   
,anniversary ,meeting of the ,geological
 ,society seems to be an occasion well  
suited for an undertaking of this       
kind--for an inquiry1 in fact1 into the 

nature and value of the present results 
of paleontological investigation2 and   
the more so1 as all those who have paid 
close attention to the late             
multitudinous discussions in which      
paleontology is implicated1 must have   
felt the urgent necessity of some such  
scrutiny4  ,first in order1 as the most 
definite and unquestionable of all the  
results of paleontology1 must be        
mentioned the immense extension and     
impulse given to botany1 zoology1 and   
comparative anatomy1 by the             
investigation of fossil remains4        
,indeed1 the mass of biological facts   
has been so greatly increased1 and the  
range of biological speculation has been
 so vastly widened1 by the researches of
 the geologist and paleontologist1 that 
it is to be feared there are naturalists
 in existence who look upon geology as  
,brindley regarded rivers4 ,rivers1 said
 the great engineer1 were made to feed  
canals2 and geology1 some seem to think1
 was solely created to advance          

comparative anatomy4  ,were such a      
thought justifiable1 it could hardly    
expect to be received with favour by    
this assembly4 ,but it is not           
justifiable4 ,your favourite science has
 her own great aims independent of all  
others2 and if1 notwithstanding her     
steady devotion to her own progress1 she
 can scatter such rich alms among her   
sisters1 it should be remembered that   
her charity is of the sort that does not
 impoverish1 but blesseth him that gives
 and him that takes4  ,regard the matter
 as we will1 however1 the facts remain4 
,nearly #dj1jjj species of animals and  
plants have been added to the ,systema  
,naturae by paleontologic research4     
,this is a living population equivalent 
to that of a new continent in mere      
number2 equivalent to that of a new     
hemisphere1 if we take into account the 
small population of insects as yet found
 fossil1 and the large proportion and   
peculiar organization of many of the    
,vertebrata4  ,but1 beyond this1 it is  

perhaps not too much to say that1 except
 for the necessity of interpreting      
paleontologic facts1 the laws of        
distribution would have received less   
careful study2 while few comparative    
anatomists 7and those not of the first  
order7 would have been induced by mere  
love of detail1 as such1 to study the   
minutiae of osteology1 were it not that 
in such minutiae lie the only keys to   
the most interesting riddles offered by 
the extinct animal world4  ,these       
assuredly are great and solid gains4    
,surely it is matter for no small       
congratulation that in half a century   
7for paleontology1 though it dawned     
earlier1 came into full day only with   
,cuvier7 a subordinate branch of biology
 should have doubled the value and the  
interest of the whole group of sciences 
to which it belongs4  ,but this is not  
all4 ,allied with geology1 paleontology 
has established two laws of inestimable 
importance3 the first1 that one and the 
same area of the earth's surface has    

been successively occupied by very      
different kinds of living beings2 the   
second1 that the order of succession    
established in one locality holds good1 
approximately1 in all4  ,the first of   
these laws is universal and             
irreversible2 the second is an induction
 from a vast number of observations1    
though it may possibly1 and even        
probably1 have to admit of exceptions4  
,as a consequence of the second law1 it 
follows that a peculiar relation        
frequently subsists between series of   
strata1 containing organic remains1 in  
different localities4 ,the series       
resemble one another1 not only in virtue
 of a general resemblance of the organic
 remains in the two1 but also in virtue 
of a resemblance in the order and       
character of the serial succession in   
each4 ,there is a resemblance of        
arrangement2 so that the separate terms 
of each series1 as well as the whole    
series1 exhibit a correspondence4       
,succession implies time2 the lower     

members of a series of sedimentary rocks
 are certainly older than the upper2 and
 when the notion of age was once        
introduced as the equivalent of         
succession1 it was no wonder that       
correspondence in succession came to be 
looked upon as a correspondence in age1 
or contemporaneity4 ,and1 indeed1 so    
long as relative age only is spoken of1 
correspondence in succession 'is'       
correspondence in age2 it is 'relative' 
contemporaneity4  ,but it would have    
been very much better for geology if so 
loose and ambiguous a word as           
contemporaneous had been excluded from  
her terminology1 and if1 in its stead1  
some term expressing similarity of      
serial relation1 and excluding the      
notion of time altogether1 had been     
employed to denote correspondence in    
position in two or more series of       
strata4  ,in anatomy1 where such        
correspondence of position has          
constantly to be spoken of1 it is       
denoted by the word homology and its    

derivatives2 and for ,geology 7which    
after all is only the anatomy and       
physiology of the earth7 it might be    
well to invent some single word1 such as
 homotaxis 7similarity of order71 in    
order to express an essentially similar 
idea4 ,this1 however1 has not been done1
 and most probably the inquiry will at  
once be made--,to what end burden       
science with a new and strange term in  
place of one old1 familiar1 and part of 
our common language8  ,the reply to this
 question will become obvious as the    
inquiry into the results of paleontology
 is pushed further4  ,those whose       
business it is to acquaint themselves   
specially with the works of             
paleontologists1 in fact1 will be fully 
aware that very few1 if any1 would rest 
satisfied with such a statement of the  
conclusions of their branch of biology  
as that which has just been given4  ,our
 standard repertories of paleontology   
profess to teach us far higher          
things--to disclose the entire          

succession of living forms upon the     
surface of the globe2 to tell us of a   
wholly different distribution of        
climatic conditions in ancient times2 to
 reveal the character of the first of   
all living existences2 and to trace out 
the law of progress from them to us4    
,it may not be unprofitable to bestow on
 these professions a somewhat more      
critical examination than they have     
hitherto received1 in order to ascertain
 how far they rest on an irrefragable   
basis2 or whether1 after all1 it might  
not be well for paleontologists to learn
 a little more carefully that scientific
 ars artium1 the art of saying ,i don't 
know4 ,and to this end let us define    
somewhat more exactly the extent of     
these pretensions of paleontology4      
,every one is aware that ,professor     
,bronn's ',untersuchungen' and          
,professor ,pictet's ',traite de        
,paleontologie' are works of standard   
authority1 familiarly consulted by every
 working paleontologist4 ,it is         

desirable to speak of these excellent   
books1 and of their distinguished       
authors1 with the utmost respect1 and in
 a tone as far as possible removed from 
carping criticism2 indeed1 if they are  
specially cited in this place1 it is    
merely in justification of the assertion
 that the following propositions1 which 
may be found implicitly1 or explicitly1 
in the works in question1 are regarded  
by the mass of paleontologists and      
geologists1 not only on the ,continent  
but in this country1 as expressing some 
of the best-established results of      
paleontology4 ,thus3--  ,animals and    
plants began their existence together1  
not long after the commencement of the  
deposition of the sedimentary rocks2 and
 then succeeded one another1 in such a  
manner1 that totally distinct faunae and
 florae occupied the whole surface of   
the earth1 one after the other1 and     
during distinct epochs of time4  ,a     
geological formation is the sum of all  
the strata deposited over the whole     

surface of the earth during one of these
 epochs3 a geological fauna or flora is 
the sum of all the species of animals or
 plants which occupied the whole surface
 of the globe1 during one of these      
epochs4  ,the population of the earth's 
surface was at first very similar in all
 parts1 and only from the middle of the 
,tertiary epoch onwards1 began to show a
 distinct distribution in zones4  ,the  
constitution of the original population1
 as well as the numerical proportions of
 its members1 indicates a warmer and1 on
 the whole1 somewhat tropical climate1  
which remained tolerably equable        
throughout the year4 ,the subsequent    
distribution of living beings in zones  
is the result of a gradual lowering of  
the general temperature1 which first    
began to be felt at the poles4  ,it is  
not now proposed to inquire whether     
these doctrines are true or false2 but  
to direct your attention to a much      
simpler though very essential           
preliminary question--,what is their    

logical basis8 what are the fundamental 
assumptions upon which they all         
logically depend8 and what is the       
evidence on which those fundamental     
propositions demand our assent8  ,these 
assumptions are two3 the first1 that the
 commencement of the geological record  
is coeval with the commencement of life 
on the globe2 the second1 that          
geological contemporaneity is the same  
thing as chronological synchrony4       
,without the first of these assumptions 
there would of course be no ground for  
any statement respecting the            
commencement of life2 without the       
second1 all the other statements cited1 
every one of which implies a knowledge  
of the state of different parts of the  
earth at one and the same time1 will be 
no less devoid of demonstration4  ,the  
first assumption obviously rests        
entirely on negative evidence4 ,this is1
 of course1 the only evidence that ever 
can be available to prove the           
commencement of any series of phenomena2

 but1 at the same time1 it must be      
recollected that the value of negative  
evidence depends entirely on the amount 
of positive corroboration it receives4  
,if ,a ,b wishes to prove an 'alibi'1 it
 is of no use for him to get a thousand 
witnesses simply to swear that they did 
not see him in such and such a place1   
unless the witnesses are prepared to    
prove that they must have seen him had  
he been there4 ,but the evidence that   
animal life commenced with the          
,lingula-flags1 'e4g4'1 would seem to be
 exactly of this unsatisfactory         
uncorroborated sort4 ,the ,cambrian     
witnesses simply swear they haven't seen
 anybody their way2 upon which the      
counsel for the other side immediately  
puts in ten or twelve thousand feet of  
,devonian sandstones to make oath they  
never saw a fish or a mollusk1 though   
all the world knows there were plenty in
 their time4  ,but then it is urged     
that1 though the ,devonian rocks in one 
part of the world exhibit no fossils1 in

 another they do1 while the lower       
,cambrian rocks nowhere exhibit fossils1
 and hence no living being could have   
existed in their epoch4  ,to this there 
are two replies3 the first1 that the    
observational basis of the assertion    
that the lowest rocks are nowhere       
fossiliferous is an amazingly small one1
 seeing how very small an area1 in      
comparison to that of the whole world1  
has yet been fully searched2 the second1
 that the argument is good for nothing  
unless the unfossiliferous rocks in     
question were not only 'contemporaneous'
 in the geological sense1 but           
'synchronous' in the chronological      
sense4 ,to use the 'alibi' illustration 
again4 ,if a man wishes to prove he was 
in neither of two places1 ,a and ,b1 on 
a given day1 his witnesses for each     
place must be prepared to answer for the
 whole day4 ,if they can only prove that
 he was not at ,a in the morning1 and   
not at ,b in the afternoon1 the evidence
 of his absence from both is 'nil'1     

because he might have been at ,b in the 
morning and at ,a in the afternoon4     
,thus everything depends upon the       
validity of the second assumption4 ,and 
we must proceed to inquire what is the  
real meaning of the word contemporaneous
 as employed by geologists4 ,to this end
 a concrete example may be taken4  ,the 
,lias of ,england and the ,lias of      
,germany1 the ,cretaceous rocks of      
,britain and the ,cretaceous rocks of   
,southern ,india1 are termed by         
geologists contemporaneous formations2  
but whenever any thoughtful geologist is
 asked whether he means to say that they
 were deposited synchronously1 he says1 
,no1--only within the same great epoch4 
,and if1 in pursuing the inquiry1 he is 
asked what may be the approximate value 
in time of a great epoch--whether it    
means a hundred years1 or a thousand1 or
 a million1 or ten million years--his   
reply is1 ,i cannot tell4  ,if the      
further question be put1 whether        
physical geology is in possession of any

 method by which the actual synchrony   
7or the reverse7 of any two distant     
deposits can be ascertained1 no such    
method can be heard of2 it being        
admitted by all the best authorities    
that neither similarity of mineral      
composition1 nor of physical character1 
nor even direct continuity of stratum1  
are 'absolute' proofs of the synchronism
 of even approximated sedimentary       
strata3 while1 for distant deposits1    
there seems to be no kind of physical   
evidence attainable of a nature         
competent to decide whether such        
deposits were formed simultaneously1 or 
whether they possess any given          
difference of antiquity4 ,to return to  
an example already given3 ,all competent
 authorities will probably assent to the
 proposition that physical geology does 
not enable us in any way to reply to    
this question--,were the ,british       
,cretaceous rocks deposited at the same 
time as those of ,india1 or are they a  
million of years younger or a million of

 years older8  ,is paleontology able to 
succeed where physical geology fails8   
,standard writers on paleontology1 as   
has been seen1 assume that she can4     
,they take it for granted1 that deposits
 containing similar organic remains are 
synchronous--at any rate in a broad     
sense2 and yet1 those who will study the
 eleventh and twelfth chapters of ,sir  
,henry ,de ,la ,beche's remarkable      
',researches in ,theoretical ,geology'1 
published now nearly thirty years ago1  
and will carry out the arguments there  
most luminously stated1 to their logical
 consequences1 may very easily convince 
themselves that even absolute identity  
of organic contents is no proof of the  
synchrony of deposits1 while absolute   
diversity is no proof of difference of  
date4 ,sir ,henry ,de ,la ,beche goes   
even further1 and adduces conclusive    
evidence to show that the different     
parts of one and the same stratum1      
having a similar composition throughout1
 containing the same organic remains1   

and having similar beds above and below 
it1 may yet differ to any conceivable   
extent in age4  ,edward ,forbes was in  
the habit of asserting that the         
similarity of the organic contents of   
distant formations was 'prima facie'    
evidence1 not of their similarity1 but  
of their difference of age2 and holding 
as he did the doctrine of single        
specific centres1 the conclusion was as 
legitimate as any other2 for the two    
districts must have been occupied by    
migration from one of the two1 or from  
an intermediate spot1 and the chances   
against exact coincidence of migration  
and of imbedding are infinite4  ,in     
point of fact1 however1 whether the     
hypothesis of single or of multiple     
specific centres be adopted1 similarity 
of organic contents cannot possibly     
afford any proof of the synchrony of the
 deposits which contain them2 on the    
contrary1 it is demonstrably compatible 
with the lapse of the most prodigious   
intervals of time1 and with the         

interposition of vast changes in the    
organic and inorganic worlds1 between   
the epochs in which such deposits were  
formed4  ,on what amount of similarity  
of their faunae is the doctrine of the  
contemporaneity of the ,european and of 
the ,north ,american ,silurians based8  
,in the last edition of ,sir ,charles   
,lyell's ',elementary ,geology' it is   
stated1 on the authority of a former    
,president of this ,society1 the late   
,daniel ,sharpe1 that between #cj and   
#dj per cent4 of the species of         
,silurian ,mollusca are common to both  
sides of the ,atlantic4 ,by way of due  
allowance for further discovery1 let us 
double the lesser number and suppose    
that #fj per cent4 of the species are   
common to the ,north ,american and the  
,british ,silurians4 ,sixty per cent4 of
 species in common is1 then1 proof of   
contemporaneity4  ,now suppose that1 a  
million or two of years hence1 when     
,britain has made another dip beneath   
the sea and has come up again1 some     

geologist applies this doctrine1 in     
comparing the strata laid bare by the   
upheaval of the bottom1 say1 of ,st4    
,george's ,channel with what may then   
remain of the ,suffolk ,crag4 ,reasoning
 in the same way1 he will at once decide
 the ,suffolk ,crag and the ,st4        
,george's ,channel beds to be           
contemporaneous2 although we happen to  
know that a vast period 7even in the    
geological sense7 of time1 and physical 
changes of almost unprecedented extent1 
separate the two4  ,but if it be a      
demonstrable fact that strata containing
 more than #fj or #gj per cent4 of      
species of ,mollusca in common1 and     
comparatively close together1 may yet be
 separated by an amount of geological   
time sufficient to allow of some of the 
greatest physical changes the world has 
seen1 what becomes of that sort of      
contemporaneity the sole evidence of    
which is a similarity of facies1 or the 
identity of half a dozen species1 or of 
a good many genera8  ,and yet there is  

no better evidence for the              
contemporaneity assumed by all who adopt
 the hypothesis of universal faunae and 
florae1 of a universally uniform        
climate1 and of a sensible cooling of   
the globe during geological time4       
,there seems1 then1 no escape from the  
admission that neither physical geology1
 nor paleontology1 possesses any method 
by which the absolute synchronism of two
 strata can be demonstrated4 ,all that  
geology can prove is local order of     
succession4 ,it is mathematically       
certain that1 in any given vertical     
linear section of an undisturbed series 
of sedimentary deposits1 the bed which  
lies lowest is the oldest4 ,in many     
other vertical linear sections of the   
same series1 of course1 corresponding   
beds will occur in a similar order2 but1
 however great may be the probability1  
no man can say with absolute certainty  
that the beds in the two sections were  
synchronously deposited4 ,for areas of  
moderate extent1 it is doubtless true   

that no practical evil is likely to     
result from assuming the corresponding  
beds to be synchronous or strictly      
contemporaneous2 and there are          
multitudes of accessory circumstances   
which may fully justify the assumption  
of such synchrony4 ,but the moment the  
geologist has to deal with large areas1 
or with completely separated deposits1  
the mischief of confounding that        
homotaxis or similarity of arrangement1 
which 'can' be demonstrated1 with       
synchrony or identity of date1 for which
 there is not a shadow of proof1 under  
the one common term of contemporaneity  
becomes incalculable1 and proves the    
constant source of gratuitous           
speculations4  ,for anything that       
geology or paleontology are able to show
 to the contrary1 a ,devonian fauna and 
flora in the ,british ,islands may have 
been contemporaneous with ,silurian life
 in ,north ,america1 and with a         
,carboniferous fauna and flora in       
,africa4 ,geographical provinces and    

zones may have been as distinctly marked
 in the ,paleozoic epoch as at present1 
and those seemingly sudden appearances  
of new genera and species1 which we     
ascribe to new creation1 may be simple  
results of migration4  ,it may be so2 it
 may be otherwise4 ,in the present      
condition of our knowledge and of our   
methods1 one verdict--not proven1 and   
not provable--must be recorded against  
all the grand hypotheses of the         
paleontologist respecting the general   
succession of life on the globe4 ,the   
order and nature of terrestrial life1 as
 a whole1 are open questions4 ,geology  
at present provides us with most        
valuable topographical records1 but she 
has not the means of working them into a
 universal history4 ,is such a universal
 history1 then1 to be regarded as       
unattainable8 ,are all the grandest and 
most interesting problems which offer   
themselves to the geological student    
essentially insoluble8 ,is he in the    
position of a scientific                

,tantalus--doomed always to thirst for a
 knowledge which he cannot obtain8 ,the 
reverse is to be hoped2 nay1 it may not 
be impossible to indicate the source    
whence help will come4  ,in commencing  
these remarks1 mention was made of the  
great obligations under which the       
naturalist lies to the geologist and    
paleontologist4 ,assuredly the time will
 come when these obligations will be    
repaid tenfold1 and when the maze of the
 world's past history1 through which the
 pure geologist and the pure            
paleontologist find no guidance1 will be
 securely threaded by the clue furnished
 by the naturalist4  ,all who are       
competent to express an opinion on the  
subject are1 at present1 agreed that the
 manifold varieties of animal and       
vegetable form have not either come into
 existence by chance1 nor result from   
capricious exertions of creative power2 
but that they have taken place in a     
definite order1 the statement of which  
order is what men of science term a     

natural law4 ,whether such a law is to  
be regarded as an expression of the mode
 of operation of natural forces1 or     
whether it is simply a statement of the 
manner in which a supernatural power has
 thought fit to act1 is a secondary     
question1 so long as the existence of   
the law and the possibility of its      
discovery by the human intellect are    
granted4 ,but he must be a half-hearted 
philosopher who1 believing in that      
possibility1 and having watched the     
gigantic strides of the biological      
sciences during the last twenty years1  
doubts that science will sooner or later
 make this further step1 so as to become
 possessed of the law of evolution of   
organic forms--of the unvarying order of
 that great chain of causes and effects 
of which all organic forms1 ancient and 
modern1 are the links4 ,and then1 if    
ever1 we shall be able to begin to      
discuss1 with profit1 the questions     
respecting the commencement of life1 and
 the nature of the successive           

populations of the globe1 which so many 
seem to think are already answered4     
,the preceding arguments make no        
particular claim to novelty2 indeed they
 have been floating more or less        
distinctly before the minds of          
geologists for the last thirty years2   
and if1 at the present time1 it has     
seemed desirable to give them more      
definite and systematic expression1 it  
is because paleontology is every day    
assuming a greater importance1 and now  
requires to rest on a basis the firmness
 of which is thoroughly well assured4   
,among its fundamental conceptions1     
there must be no confusion between what 
is certain and what is more or less     
probable4 #b ,but1 pending the          
construction of a surer foundation than 
paleontology now possesses1 it may be   
instructive1 assuming for the nonce the 
general correctness of the ordinary     
hypothesis of geological                
contemporaneity1 to consider whether the
 deductions which are ordinarily drawn  

from the whole body of paleontologic    
facts are justifiable4  ,the evidence on
 which such conclusions are based is of 
two kinds1 negative and positive4 ,the  
value of negative evidence1 in          
connection with this inquiry1 has been  
so fully and clearly discussed in an    
address from the chair of this ,society 
#c1 which none of us have forgotten1    
that nothing need at present be said    
about it2 the more1 as the              
considerations which have been laid     
before you have certainly not tended to 
increase your estimation of such        
evidence4 ,it will be preferable to turn
 to the positive facts of paleontology1 
and to inquire what they tell us4  ,we  
are all accustomed to speak of the      
number and the extent of the changes in 
the living population of the globe      
during geological time as something     
enormous3 and indeed they are so1 if we 
regard only the negative differences    
which separate the older rocks from the 
more modern1 and if we look upon        

specific and generic changes as great   
changes1 which from one point of view1  
they truly are4 ,but leaving the        
negative differences out of             
consideration1 and looking only at the  
positive data furnished by the fossil   
world from a broader point of view--from
 that of the comparative anatomist who  
has made the study of the greater       
modifications of animal form his chief  
business--a surprise of another kind    
dawns upon the mind2 and under 'this'   
aspect the smallness of the total change
 becomes as astonishing as was its      
greatness under the other4  ,there are  
two hundred known orders of plants2 of  
these not one is certainly known to     
exist exclusively in the fossil state4  
,the whole lapse of geological time has 
as yet yielded not a single new ordinal 
type of vegetable structure4 #d  ,the   
positive change in passing from the     
recent to the ancient animal world is   
greater1 but still singularly small4 ,no
 fossil animal is so distinct from those

 now living as to require to be arranged
 even in a separate class from those    
which contain existing forms4 ,it is    
only when we come to the orders1 which  
may be roughly estimated at about a     
hundred and thirty1 that we meet with   
fossil animals so distinct from those   
now living as to require orders for     
themselves2 and these do not amount1 on 
the most liberal estimate1 to more than 
about #aj per cent4 of the whole4       
,there is no certainly known extinct    
order of ,protozoa2 there is but one    
among the ,coelenterata--that of the    
rugose corals2 there is none among the  
,mollusca2 there are three1 the         
,cystidea1 ,blastoidea1 and             
,edrioasterida1 among the ,echinoderms2 
and two1 the ,trilobita and             
,eurypterida1 among the ,crustacea2     
making altogether five for the great    
sub-kingdom of ,annulosa4 ,among        
,vertebrates there is no ordinally      
distinct fossil fish3 there is only one 
extinct order of ,amphibia--the         

,labyrinthodonts2 but there are at least
 four distinct orders of ,reptilia1 viz4
 the ,ichthyosauria1 ,plesiosauria1     
,pterosauria1 ,dinosauria1 and perhaps  
another or two4 ,there is no known      
extinct order of ,birds1 and no         
certainly known extinct order of        
,mammals1 the ordinal distinctness of   
the ,toxodontia being doubtful4  ,the   
objection that broad statements of this 
kind1 after all1 rest largely on        
negative evidence is obvious1 but it has
 less force than may at first be        
supposed2 for1 as might be expected from
 the circumstances of the case1 we      
possess more abundant positive evidence 
regarding ,fishes and marine ,mollusks  
than respecting any other forms of      
animal life2 and yet these offer us1    
through the whole range of geological   
time1 no species ordinally distinct from
 those now living2 while the far less   
numerous class of ,echinoderms presents 
three2 and the ,crustacea two1 such     
orders1 though none of these come down  

later than the ,paleozoic age4 ,lastly1 
the ,reptilia present the extraordinary 
and exceptional phenomenon of as many   
extinct as existing orders1 if not more2
 the four mentioned maintaining their   
existence from the ,lias to the ,chalk  
inclusive4  ,some years ago one of your 
,secretaries pointed out another kind of
 positive paleontologic evidence tending
 towards the same conclusion--afforded  
by the existence of what he termed      
persistent types of vegetable and of    
animal life4 #e ,he stated1 on the      
authority of ,dr4 ,hooker1 that there   
are ,carboniferous plants which appear  
to be generically identical with some   
now living2 that the cone of the        
,oolitic ',araucaria' is hardly         
distinguishable from that of an existing
 species2 that a true ',pinus' appears  
in the ,purbecks1 and a ',juglans' in   
the ,chalk2 while1 from the ,bagshot    
,sands1 a ',banksia'1 the wood of which 
is not distinguishable from that of     
species now living in ,australia1 had   

been obtained4  ,turning to the animal  
kingdom1 he affirmed the tabulate corals
 of the ,silurian rocks to be           
wonderfully like those which now exist2 
while even the families of the ,aporosa 
were all represented in the older       
,mesozoic rocks4  ,among the ,molluska  
similar facts were adduced4 ,let it be  
borne in mind that ',avicula'1          
',mytails'1 ',chiton'1 ',natica'1       
',patella'1 ',trochus'1 ',discina'1     
',orbicula'1 ',lingula'1                
',rhynchonella'1 and ',nautilus'1 all of
 which are existing 'genera'1 are given 
without a doubt as ,silurian in the last
 edition of ',siluria'2 while the       
highest forms of the highest            
,cephalopods are represented in the     
,lias by a genus1 ',belemnoteuthis'1    
which presents the closest relation to  
the existing ',loligo'4  ,the two       
highest groups of the ,annulosa1 the    
,insecta and the ,arachnida1 are        
represented in the ,coal1 either by     
existing genera1 or by forms differing  

from existing genera in quite minor     
peculiarities4  ,turning to the         
,vertebrata1 the only ,paleozoic        
,elasmobranch ,fish of which we have any
 complete knowledge is the ,devonian and
 ,carboniferous ',pleuracanthus'1 which 
differs no more from existing ,sharks   
than these do from one another4  ,again1
 vast as is the number of undoubtedly   
,ganoid fossil ,fishes1 and great as is 
their range in time1 a large mass of    
evidence has recently been adduced to   
show that almost all those respecting   
which we possess sufficient information1
 are referable to the same sub-ordinal  
groups as the existing ',lepidosteus'1  
',polypterus'1 and ,sturgeon2 and that a
 singular relation obtains between the  
older and the younger ,fishes2 the      
former1 the ,devonian ,ganoids1 being   
almost all members of the same sub-order
 as ',polypterus'1 while the ,mesozoic  
,ganoids are almost all similarly allied
 to ',lepidosteus'4 #f  ,again1 what can
 be more remarkable than the singular   

constancy of structure preserved        
throughout a vast period of time by the 
family of the ,pycnodonts and by that of
 the true ,coelacanths2 the former      
persisting1 with but insignificant      
modifications1 from the ,carboniferous  
to the ,tertiary rocks1 inclusive2 the  
latter existing1 with still less change1
 from the ,carboniferous rocks to the   
,chalk1 inclusive8  ,among ,reptiles1   
the highest living group1 that of the   
,crocodilia1 is represented1 at the     
early part of the ,mesozoic epoch1 by   
species identical in the essential      
characters of their organization with   
those now living1 and differing from the
 latter only in such matters as the form
 of the articular facets of the         
vertebral centra1 in the extent to which
 the nasal passages are separated from  
the cavity of the mouth by bone1 and in 
the proportions of the limbs4  ,and even
 as regards the ,mammalia1 the scanty   
remains of ,triassic and ,oolitic       
species afford no foundation for the    

supposition that the organization of the
 oldest forms differed nearly so much   
from some of those which now live as    
these differ from one another4  ,it is  
needless to multiply these instances2   
enough has been said to justify the     
statement that1 in view of the immense  
diversity of known animal and vegetable 
forms1 and the enormous lapse of time   
indicated by the accumulation of        
fossiliferous strata1 the only          
circumstance to be wondered at is1 not  
that the changes of life1 as exhibited  
by positive evidence1 have been so      
great1 but that they have been so small4
  ,be they great or small1 however1 it  
is desirable to attempt to estimate     
them4 ,let us1 therefore1 take each     
great division of the animal world in   
succession1 and1 whenever an order or a 
family can be shown to have had a       
prolonged existence1 let us endeavour to
 ascertain how far the later members of 
the group differ from the earlier ones4 
,if these later members1 in all or in   

many cases1 exhibit a certain amount of 
modification1 the fact is1 so far1      
evidence in favour of a general law of  
change2 and1 in a rough way1 the        
rapidity of that change will be measured
 by the demonstrable amount of          
modification4 ,on the other hand1 it    
must be recollected that the absence of 
any modification1 while it may leave the
 doctrine of the existence of a law of  
change without positive support1 cannot 
possibly disprove all forms of that     
doctrine1 though it may afford a        
sufficient refutation of any of them4   
,the ,,protozoa4--,the ,protozoa are    
represented throughout the whole range  
of geological series1 from the ,lower   
,silurian formation to the present day4 
,the most ancient forms recently made   
known by ,ehrenberg are exceedingly like
 those which now exist3 no one has ever 
pretended that the difference between   
any ancient and any modern ,foraminifera
 is of more than generic value1 nor are 
the oldest ,foraminifera either simpler1

 more embryonic1 or less differentiated1
 than the existing forms4  ,the         
,,coelenterata4--,the ,tabulate ,corals 
have existed from the ,silurian epoch to
 the present day1 but ,i am not aware   
that the ancient ',heliolites' possesses
 a single mark of a more embryonic or   
less differentiated character1 or less  
high organization1 than the existing    
',heliopora'4 ,as for the ,aporose      
,corals1 in what respect is the         
,silurian ',paleocyclus' less highly    
organized or more embryonic than the    
modern ',fungia'1 or the ,liassic       
,aporosa than the existing members of   
the same families8  ,the                
',mollusca'4--,in what sense is the     
living ',waldheimia' less embryonic1 or 
more specialized2 than the paleozoic    
',spirifer'2 or the existing            
',rhynchonellae'1 ',craniae'1           
',discinae'1 ',lingulae'1 than the      
,silurian species of the same genera8   
,in what sense can ',loligo' or         
',spirula' be said to be more           

specialized1 or less embryonic1 than    
',belemnites'2 or the modern species of 
,lamellibranch and ,gasteropod genera1  
than the ,silurian species of the same  
genera8  ,the ,,annulosa4--,the         
,carboniferous ,insecta and ,arachnida  
are neither less specialized1 nor more  
embryonic1 than these that now live1 nor
 are the ,liassic ,cirripedia and       
,macrura2 while several of the          
,brachyura1 which appear in the ,chalk1 
belong to existing genera2 and none     
exhibit either an intermediate1 or an   
embryonic1 character4  ,the             
,,vertebrara4--,among fishes ,i have    
referred to the ,coelacanthini          
7comprising the genera ',coelacanthus'1 
',holophagus'1 ',undina'1 and           
',macropoma'7 as affording an example of
 a persistent type2 and it is most      
remarkable to note the smallness of the 
differences between any of these fishes 
7affecting at most the proportions of   
the body and fins1 and the character and
 sculpture of the scales71              

notwithstanding their enormous range in 
time4 ,in all the essentials of its very
 peculiar structure1 the ',macropoma' of
 the ,chalk is identical with the       
',coelacanthus' of the ,coal4 ,look at  
the genus ',lepidotus'1 again1          
persisting without a modification of    
importance from the ,liassic to the     
,eocene formations inclusive4  ,or among
 the ,teleostei--in what respect is the 
',beryx' of the ,chalk more embryonic1  
or less differentiated1 than ',beryx    
lineatus' of ,king ,george's ,sound8    
,or to turn to the higher               
,vertebrata--in what sense are the      
,liassic ,chelonia inferior to those    
which now exist8 ,how are the           
,cretaceous ,ichthyosauria1             
,plesiosauria1 or ,pterosauria less     
embryonic1 or more differentiated1      
species than those of the ,lias8  ,or   
lastly1 in what circumstance is the     
',phascolotherium' more embryonic1 or of
 a more generalized type1 than the      
modern ,opossum2 or a ',lophiodon'1 or a

 ',paleotherium'1 than a modern         
',tapirus' or ',hyrax'8  ,these examples
 might be almost indefinitely           
multiplied1 but surely they are         
sufficient to prove that the only safe  
and unquestionable testimony we can     
procure--positive evidence--fails to    
demonstrate any sort of progressive     
modification towards a less embryonic1  
or less generalised1 type in a great    
many groups of animals of long-continued
 geological existence4 ,in these groups 
there is abundant evidence of           
variation--none of what is ordinarily   
understood as progression2 and1 if the  
known geological record is to be        
regarded as even any considerable       
fragment of the whole1 it is            
inconceivable that any theory of a      
necessarily progressive development can 
stand1 for the numerous orders and      
families cited afford no trace of such a
 process4  ,but it is a most remarkable 
fact1 that1 while the groups which have 
been mentioned1 and many besides1       

exhibit no sign of progressive          
modification1 there are others1         
co-existing with them1 under the same   
conditions1 in which more or less       
distinct indications of such a process  
seems to be traceable4 ,among such      
indications ,i may remind you of the    
predominance of ,holostome ,gasteropoda 
in the older rocks as compared with that
 of ,siphonostome ,gasteropoda in the   
later4 ,a case less open to the         
objection of negative evidence1 however1
 is that afforded by the                
,tetrabranchiate ,cephalopoda1 the forms
 of the shells and of the septal sutures
 exhibiting a certain increase of       
complexity in the newer genera4 ,here1  
however1 one is met at once with the    
occurrence of ',orthoceras' and         
',baculites' at the two ends of the     
series1 and of the fact that one of the 
simplest ,genera1 ',nautilus'1 is that  
which now exists4  ,the ,crinoidea1 in  
the abundance of stalked forms in the   
ancient formations as compared with     

their present rarity1 seem to present us
 with a fair case of modification from a
 more embryonic towards a less embryonic
 condition4 ,but then1 on careful       
consideration of the facts1 the         
objection arises that the stalk1 calyx1 
and arms of the paleozoic ,crinoid are  
exceedingly different from the          
corresponding organs of a larval        
',comatula'2 and it might with perfect  
justice be argued that ',actinocrinus'  
and ',eucalyptocrinus'1 for example1    
depart to the full as widely1 in one    
direction1 from the stalked embryo of   
',comatula'1 as ',comatula' itself does 
in the other4  ,the ,echinidea1 again1  
are frequently quoted as exhibiting a   
gradual passage from a more generalized 
to a more specialized type1 seeing that 
the elongated1 or oval1 ,spatangoids    
appear after the spheroidal ,echinoids4 
,but here it might be argued1 on the    
other hand1 that the spheroidal         
,echinoids1 in reality1 depart further  
from the general plan and from the      

embryonic form than the elongated       
,spatangoids do2 and that the peculiar  
dental apparatus and the pedicellariae  
of the former are marks of at least as  
great differentiation as the petaloid   
ambulacra and semitae of the latter4    
,once more1 the prevalence of ,macrurous
 before ,brachyurous ,podophthalmia is1 
apparently1 a fair piece of evidence in 
favour of progressive modification in   
the same order of ,crustacea2 and yet   
the case will not stand much sifting1   
seeing that the ,macrurous              
,podophthalmia depart as far in one     
direction from the common type of       
,podophthalmia1 or from any embryonic   
condition of the ,brachyura1 as the     
,brachyura do in the other2 and that the
 middle terms between ,macrura and      
,brachyura--the ,anomura--are little    
better represented in the older         
,mesozoic rocks than the ,brachyura are4
  ,none of the cases of progressive     
modification which are cited from among 
the ,invertebrata appear to me to have a

 foundation less open to criticism than 
these2 and if this be so1 no careful    
reasoner would1 ,i think1 be inclined to
 lay very great stress upon them4 ,among
 the ,vertebrata1 however1 there are a  
few examples which appear to be far less
 open to objection4  ,it is1 in fact1   
true of several groups of ,vertebrata   
which have lived through a considerable 
range of time1 that the endoskeleton    
7more particularly the spinal column7 of
 the older genera presents a less       
ossified1 and1 so far1 less             
differentiated1 condition than that of  
the younger genera4 ,thus the ,devonian 
,ganoids1 though almost all members of  
the same sub-order as ',polypterus'1 and
 presenting numerous important          
resemblances to the existing genus1     
which possesses biconcave vertebrae1    
are1 for the most part1 wholly devoid of
 ossified vertebral centra4 ,the        
,mesozoic ,lepidosteidae1 again1 have1  
at most1 biconcave vertebrae1 while the 
existing ',lepidosteus' has             

,salamandroid1 opisthocoelous1          
vertebrae4 ,so1 none of the ,paleozoic  
,sharks have shown themselves to be     
possessed of ossified vertebrae1 while  
the majority of modern ,sharks possess  
such vertebrae4 ,again1 the more ancient
 ,crocodilia and ,lacertilia have       
vertebrae with the articular facets of  
their centra flattened or biconcave1    
while the modern members of the same    
group have them procoelous4 ,but the    
most remarkable examples of progressive 
modification of the vertebral column1 in
 correspondence with geological age1 are
 those afforded by the ,pycnodonts among
 fish1 and the ,labyrinthodonts among   
,amphibia4  ,the late able ichthyologist
 ,heckel pointed out the fact1 that1    
while the ,pycnodonts never possess true
 vertebral centra1 they differ in the   
degree of expansion and extension of the
 ends of the bony arches of the         
vertebrae upon the sheath of the        
notochord2 the ,carboniferous forms     
exhibiting hardly any such expansion1   

while the ,mesozoic genera present a    
greater and greater development1 until1 
in the ,tertiary forms1 the expanded    
ends become suturally united so as to   
form a sort of false vertebra4 ,hermann 
von ,meyer1 again1 to whose luminous    
researches we are indebted for our      
present large knowledge of the          
organization of the older               
,labyrinthodonts1 has proved that the   
,carboniferous ',archegosaurus' had very
 imperfectly developed vertebral centra1
 while the ,triassic ',mastodonsaurus'  
had the same parts completely ossified4 
#g  ,the regularity and evenness of the 
dentition of the ',anoplotherium'1 as   
contrasted with that of existing        
,artiodactyles1 and the assumed nearer  
approach of the dentition of certain    
ancient ,carnivores to the typical      
arrangement1 have also been cited as    
exemplifications of a law of progressive
 development1 but ,i know of no other   
cases based on positive evidence which  
are worthy of particular notice4  ,what1

 then1 does an impartial survey of the  
positively ascertained truths of        
paleontology testify in relation to the 
common doctrines of progressive         
modification1 which suppose that        
modification to have taken place by a   
necessary progress from more to less    
embryonic forms1 or from more to less   
generalized types1 within the limits of 
the period represented by the           
fossiliferous rocks8  ,it negatives     
those doctrines2 for it either shows us 
no evidence of any such modification1 or
 demonstrates it to have been very      
slight2 and as to the nature of that    
modification1 it yields no evidence     
whatsoever that the earlier members of  
any long-continued group were more      
generalized in structure than the later 
ones4 ,to a certain extent1 indeed1 it  
may be said that imperfect ossification 
of the vertebral column is an embryonic 
character2 but1 on the other hand1 it   
would be extremely incorrect to suppose 
that the vertebral columns of the older 

,vertebrata are in any sense embryonic  
in their whole structure4  ,obviously1  
if the earliest fossiliferous rocks now 
known are coeval with the commencement  
of life1 and if their contents give us  
any just conception of the nature and   
the extent of the earliest fauna and    
flora1 the insignificant amount of      
modification which can be demonstrated  
to have taken place in any one group of 
animals1 or plants1 is quite            
incompatible with the hypothesis that   
all living forms are the results of a   
necessary process of progressive        
development1 entirely comprised within  
the time represented by the             
fossiliferous rocks4  ,contrariwise1 any
 admissible hypothesis of progressive   
modification must be compatible with    
persistence without progression1 through
 indefinite periods4 ,and should such an
 hypothesis eventually be proved to be  
true1 in the only way in which it can be
 demonstrated1 viz4 by observation and  
experiment upon the existing forms of   

life1 the conclusion will inevitably    
present itself1 that the ,paleozoic1    
,mesozoic1 and ,cainozoic faunae and    
florae1 taken together1 bear somewhat   
the same proportion to the whole series 
of living beings which have occupied    
this globe1 as the existing fauna and   
flora do to them4  ,such are the results
 of paleontology as they appear1 and    
have for some years appeared1 to the    
mind of an inquirer who regards that    
study simply as one of the applications 
of the great biological sciences1 and   
who desires to see it placed upon the   
same sound basis as other branches of   
physical inquiry4 ,if the arguments     
which have been brought forward are     
valid1 probably no one1 in view of the  
present state of opinion1 will be       
inclined to think the time wasted which 
has been spent upon their elaboration4  
,footnote #a3 ,the ,anniversary ,address
 to the ,geological ,society for #ahfb4 
,footnote #b3 le plus grand service     
qu'on puisse rendre a la science est d'y

 faire place nette avant d'y rien       
construire4--,,cuvier  ,footnote #c3    
,anniversary ,address for #ahea1        
',quart4 ,journ4 ,geol4 ,soc4' vol4 vii4
  ,footnote #d3 ,see ,hooker's          
',introductory ,essay to the ,flora of  
,tasmania'1 p4 xxiii4  ,footnote #e3    
,see the abstract of a ,lecture ,on the 
,persistent ,types of ,animal ,life1 in 
the ',notices of the ,meetings of the   
,royal ,institution of ,great           
,britain'4--,june #c1 #ahei1 vol4 iii4  
p4 #aea4  ,footnote #f3 ,memoirs of the 
,geological ,survey of the ,united      
,kingdom4--,decade x4 ,preliminary      
,essay upon the ,systematic ,arrangement
 of the ,fishes of the ,devonian ,epoch4
  ,footnote #g3 ,as the ,address is     
passing through the press 7,march #g1   
#ahfb71 evidence lies before me of the  
existence of a new ,labyrinthodont      
7',pholidogaster'71 from the ,edinburgh 
coal-field1 with well-ossified vertebral
 centra4