250 On the Question — Is there Identity between the 



researches on fossil fishes, has not found among those of the 

 secondary series more than a single species which can be 

 connected with the races of our own day. 



This exception is limited to such an insignificant number, 

 that it is probably an exception only in appearance. How 

 many characters have disappeared in the incomplete remains 

 from which we are obliged to reconstruct the beings of the 

 ancient world ! If the animals of ages so remote from us, 

 considered as identical, even after a minute comparison, were 

 to return to life, a multitude of distinctions, of which we had 

 not the least idea, would appear, and shew us how much we 

 erred respecting their pretended affinities. 



Yet the complete difference between the animals of our 

 epoch and those of the secondary and tertiary periods, has 

 not been admitted by all naturalists. It has been denied by 

 M. Ehrenberg, who has found a perfect analogy between 

 many infusoria of the cretaceous formations, and those still 

 alive. 



If it is possible to be deceived in the examination of animals 

 AS complicated as the vertebrata, how much more easy is it 

 to fall into error when attempting to determine infusoria, 

 whose diameter scarcely equals the 300th of a millimetre, 

 and whose organization is remarkable for its simplicity I 



M. Ehrenberg himself has given us a proof of the difficulty 

 of determining these infinitely minute beings. He has proved 

 that twelve species of vorticella were only different states of 

 a thirteenth species. Yet of these, a great number of differ- 

 ent groups had been formed, and the genera Eulissa, Bedella, 

 Kerobalana, Craterina, Ophridia, and Urceolaria, established 

 upon them. 



On the other hand, Mr Owen, by considering the general 

 characters of the present population of Australia, is surprised 

 that that of the later geological times could present us with 

 animals of the genera of the Mastodons. In fact, there has 

 not hitherto been found there any living pachyderm, either 

 fossil or {humatile ?) Yet the remains of a terrestrial mam- 

 mifer very analogous, in its teeth, to one of the species of 

 Mastodon common in America and Europe, have been found 

 in the ossiferous grottoes of that country. 



