Two New Species of Fossil Footmarks. 47 



from their feet. This is eminently true of birds. "Indeed," 

 says Dumeril, " it is by the form and the length of the feet, and 

 the disposition of the toes, that birds are divided into six orders," 

 &c* 5. Living animals could to a great extent be divided cor- 

 rectly into families, genera, and species, by their tracks. 6. If no 

 fossil animal is to be named until we obtain a complete descrip- 

 tion of it, then a large part of those already named, should be 

 stricken from the list of organic remains, since only fragments of 

 their skeletons have been found ; and we have the authority of 

 Cuvier for saying, that sometimes even the whole skeleton is 

 insufficient to distinguish species from species. " The differ- 

 ence," he remarks, "between two species is sometimes entirely 

 inappreciable from the skeleton. Even the genera cannot always 

 be distinguished by osteological characters."! My conviction is, 

 that not a few fossil animals have been described from characters 

 much more uncertain than those derived from well preserved 

 tracks, 7. We have the highest authority for naming animals 

 from their tracks alone. This was done by Professor Kaup, in 

 the case of the C hirotherium ; and by Professor Owen, in the 

 case of the Festudo Duncani ; the only evidence of whose ex- 

 istence is the tracks on the sandstone of Scotland.^ 8. Conven- 

 ience in writing or conversing about different kinds of these relics, 

 demands that scientific names should be attached, either to the 

 tracks or the animals that made them. In making attempts to 

 describe them without names, I have sometimes been reminded 

 of the house that Jack built, in an old nursery story : Ex gr., 

 " this is the dog that worried the cat, that killed the rat, that ate 

 the malt, that lay in the house that Jack built." 



Upon the whole, I cannot see why it is not as desirable, and as 

 consonant to the laws of zoology and comparative anatomy, to 

 derive the name of an extinct animal from its tracks, as from a 

 fragment of a skeleton. Admit that in most cases there may be 

 more danger of mistake in the former than in the latter instance : 

 yet in the first case there is almost every possible degree of un- 

 certainty as to the exact place which the animal ought to occupy. 

 But if well assured of its former existence, why should it not 

 have a name assigned it, among the preadamite inhabitants of 

 the earth, according to the rules of nomenclature derived irom 

 zoology and comparative anatomy? So far as these sciences 

 Will justify distinctions, and no farther, do I contend for Jhe 

 erection of genera and species. In the present instance, I have 

 so constructed the generic and specific names that they will hold 

 good, though future researches should prove the animals to have 

 been very different in nature from what we now suppose, k ur- 



* Elemens des Sciences Naturelles, Tome ii, p. 258, fourth edition. 



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



t Rep. of Brit. Assoc, for Advancement of Science, for 1841, p. 160. 



