WORK IN PALAZONTOLOGY 145 
occurring in the Paris Basin, it was a most valuable, 
ingenious, and yet obvious method, and even now its 
the principal rule the paleontologist follows in identt- 
fying fragments of fossils of any class. But it has its 
limitations, and it goes without saying that the more 
complete the fossil skeleton of a vertebrate, or the 
remains of an arthropod, the more complete will be 
our conception of the form of the extinct organism. 
It may be misleading in the numerous cases of 
convergence and of generalized forms which now 
abound in our paleontological collections. We can 
well understand how guarded one must be in working 
out the restorations of dinosaurs and fossil birds, of the 
Permian and Triassic theromorphs, and the Tertiary 
creodonts as compared with existing carnivora. 
As the late O. C. Marsh* observed : 
“We know to-day that unknown extinct animals 
cannot be restored from a single tooth or claw unless 
they are very similar to forms already known. Had 
discouraging the Blumenbachs and Soemmerings from giving their 
attention to this kind of work.” 
Huxley has, z#¢er alia, put the case in a somewhat similar way, to 
show that the law should at least be applied with much caution to 
unknown forms: 
“Cuvier, in the Discours sur les Révolutions dela Surface du Globe, 
strangely credits himself, and has ever since been credited by others, 
with the invention of anew method of paleontological research. But 
if you will turn to the Recherches sur les Ossemens fosstles, and watch 
Cuvier not speculating, but working, you will find that his method is 
neither more nor less than that of Steno. If he was able to make his 
famous prophecy from the jaw which lay upon the surface of a block 
of stone to the pelvis which lay hidden in it, it was not because either 
he or any one else knew, or knows, why a certain form of jaw is, as 
a rule, constantly accompanied by the presence of marsupial bones, 
but simply because experience has shown that these two structures are 
coérdinated ” (Science and Hebrew Tradition. Rise and Progress 
of Paleontology 1881, p. 23). 
* History and Methods of Paleontological Discovery (1879). 
10 
