316 Ornithichnology. 



repose much confidence in the distinct existence of the following 

 species and varieties. Indeed, had I followed my own impressions,- 

 I should have regarded some of the varieties, as species. But I pre- 

 fer to make the number too small, rather than too large. 



When I speak of species here, I mean species in oryctology, not 

 in ornithology. And I doubt not, that in perhaps every instance, 

 what I call a species in the former science, woidd be a genus in the 

 latter ; that is to say, these different tracks were made by birds that 

 were generically different. 



I am aware, that even where the whole skeletons of birds are 

 found, it is very difficult often to distinguish species. " The differ- 

 ence," says Cuvier, " between two species, is sometimes entirely 

 inappreciable from the skeleton. Even the genera cannot always 

 be distinguished by osteological characters."* Is it not then pre- 

 sumptuous to speak of distinct species when we have nothing but a 

 mere impression of the foot ? I presume that in following the indi- 

 cations derived from this single source, we cannot always avoid con- 

 founding several distinct species of birds under a single species of 

 ornithichnites : and observation upon the striking resemblance be- 

 tween the tracks of several living species of birds confirms me in this 

 opinion. But if we take into the account the size and form of the 

 track, and the distance between the successive steps, I am confident 

 we can distinguish, often between those birds that were considerably 

 unlike one another. " The places where birds live, and the man- 

 ner of their moving forward," says Dumeril, " are, so to speak, in- 

 dicated beforehand by the disposition of their feet. Indeed, it is by 

 the form, the length of the feet, and the disposition of the toes, that 

 birds are divided into six orders, &£c."f 



ORNITHICHNITES. 



1. Pachydactyli. 



O giganteus. 



O tuberosus. 



a dubius. 



2. Leptodactyli. 



O— ingens. 



a minor. 



* Ossemens Fossiles, Tome troisieme, p. 524, third edition. 



t Elemens des Sciences Naturelles, Tome II, p. 258, fourth edition. 



