THE ORIGIN OF SPECIES 543 



ated form-series were not available at the time of the " Origin " or 

 before, the evolutionist of the period could still find in paleontology 

 one sort of evidence decidedly unfavorable to the chief hypothesis then 

 opposed to his own — that of extensive " revolutions of the globe," 

 wholesale obliterations of faunas, and thorough-going new creations of 

 the entire organic world. This evidence lay in the persistence of many 

 orders and certain species through more than one geological epoch. 

 The classic of the special creation doctrine was the introduction to 

 the third edition of Cuvier's " Eecherches sur les ossements f ossiles " ; 

 and the principal argument of that work was, in the words of one of 

 Cuvier's disciples, 36 to the effect that " no fossil species, at least among 

 the two classes of mammalia and reptilia, has any analogue among liv- 

 ing species, or, in other words, that every fossil species is extinct." If 

 this could be shown by positive evidence not to be the case, one of the 

 principal supports of the special creation hypothesis was taken away 

 from. it. Huxley made much of this line of attack in a paper of 1859 

 and in his address before the Geological Society in 1862. He pointed 

 out, for example, that lingula and certain mollusca "have persisted from 

 the Silurian epoch to the present day, with so little change that com- 

 petent malacologists are sometimes puzzled to distinguish the ancient 

 from the modern species." He noted that the " group of crocodilia 

 was represented at the beginning of the Mesozoic age, if not earlier, by 

 species identical in the character of their organization with those now 

 living"; and that, probably, even certain types of the ancient mam- 

 malian fauna, such as that of the marsupialia, have persisted with no 

 greater change throughout as vast a lapse of time." 



But the argument Huxley here used had not newly become available. 

 Cuvier's generalization had gone far beyond any evidence which he had 

 offered, or which could, in the nature of the case, be offered. The 

 proposition was, indeed, insusceptible of proof, save by a sort of 

 reasoning in a circle. For when the special creationists denied the sur- 

 vival of species from one epoch to another, they were using the word 

 " species " in a sense different from that in which they, at least, usually 

 employed it. In their zoology, the final test of specific difference be- 

 tween two forms was the sterility of the hybrid. But extinct forms can 

 not be subjected to this test. In paleontology, therefore, differences of 

 species had to be determined solely on grounds of morphological dis- 

 similarity; while it was, at the same time, recognized that in living 

 animals an immense range of such dissimilarity might be consistent 

 with identity of physiological species. If the pug dog and the grey- 

 hound had been extinct, it is at least questionable whether paleontol- 

 ogists would have assigned them to the same species — especially if their 

 remains had been found at different geological horizons. Under such 



36 Flourens, " Analyse raisonge des travaux de G. Cuvier," 1841. 



