FOSSIL REPTILES. 179 



following characters, which future discoveries may, perhaps, 

 prove to be less general and less essential : — 



Five toes before ; four behind ; three toes only armed with 

 claws on each foot ; thus there are two before and one behind 

 without a claw: all the tail and the upper and under part of the 

 body covered with square scales ; the greatest part of those of the 

 back raised by longitudinal crests or ridges, projecting more or 

 less : the flanks furnished with small rounded scales only: simi- 

 lar ridges forming on the base of the tail, two crests denticulated 

 like a saw, which unite in a single one for the rest of its length : 

 the ears closed externally by two fleshy lips : the nostrils form- 

 ing a long narrow canal which opens internally in the throat : 

 the eyes having three lids : two small pouches opening under 

 the neck, and containing a musky substance. 



Their anatomy also presents characters common to all the 

 species, and which clearly distinguish their skeleton from that 

 of other saurian reptiles. These are : — 



1. The vertebrae of the neck have certain kinds of false fibs, 

 which, touching each other by their extremities, hinder the 

 animal from completely turning the head aside. 



2. The sternum is prolonged beyond the ribs, and has false 

 ribs of a description altogether peculiar, which do not articulate 

 with the vertebrae, but serve for the purpose of guarding the 

 abdomen, &c. 



The crocodiles with all these characters constitute a very 

 natural genus. This is a truth which was sufficiently percep- 

 tible to various systematic writers, but they were wrong in uniting 

 to this genus certain species which in truth possessed the cha- 

 racter assigned by their system, but which differed from the 

 genus crocodile in every other respect. 



It is not unimportant nor uninteresting to trace the steps by 

 which the Baron Cuvier was led to a just classification of these 

 animals. To arrive at the distinction of species, he commenced 

 by putting out of the investigation the long-beaked crocodiles, 

 vulgarly termed gavials, or crocodiles of the Ganges, they being 



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