Two New Species of Fossil Footmarks. AT 
from their feet. This is eminently true of birds. ‘ Indeed,” 
says Duméril, “it is by the form and the length of the feet, and 
the disposition of the toes, that birds are divided into six orders,” 
&e. iving animals could to a great extent be divided cor- 
rectly into families, genera, and species, by their tracks. 6. If no 
Cuvier for saying, that sometimes even the whole skeleton is 
insufficient to distinguish species from species. “The differ- 
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 Chirotherium; and by Professor Owen, in the 
case of the F'estudo Duncani ; the only evidence of whose ex- 
istence is the tracks on the sandstone of Scotland.t 8. Conven- 
lence 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 remind 
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 
ment of a skeleton. Admit that in most cases there may be 
he earth, according to the rules of nomenclature derived from - 
Zoology and comparative anatomy? ‘So far as the 
will justify distinctions, and no farther, do I contend for 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. Fur- 
PB oc: Saesc  e 
* Elemens des Sciences Naturelles, Tome ii, p. 258, fourth edition. 
t emens Fossiles, Tome troisiéme, p- 524 third edition. 
$ Rep. of Brit. faces for Advancement of Science, for 1841, p. 160. 
