96 FOSSIL MAMMALIA. 



fresh water. The animals whose debris are found with theirs, 

 are either terrestrial animals, and, like them, unknown; or 

 crocodiles, trionyces, and emydes, the genera of which inhabit 

 the fresh water at the present day in the torrid zone. Finally, 

 in many situations well determined, these strata are again 

 covered by strata of an origin indubitably marine. Conse- 

 quently, we find this genus of the lophiodon closely united to 

 those of the palaeotheria and anaplotheria, and other unknown 

 genera yet to be described, and which demonstrate the certainty 

 of an anterior state of animal creation, which occupied the sur- 

 face of our present continents, and which an irruption of the 

 sea overwhelmed, and covered again their debris with rocks of 

 a new origin. 



Previously to entering on any account of those more ancient 

 races, for whose discovery and description we are exclusively 

 indebted to M. Cuvier, it may be as well to take a retrospec- 

 tive glance at what we have already done, and present the 

 reader with a short recapitulation of this portion of the subject. 



We find, then, that, in the loose or ancient alluvial strata, 

 by Dr. Buckland called diluviaU those depositions which fill 

 the bottom of our vallies, and cover the superficies of our con- 

 tinents, there have been discovered, in the order of the pachy- 

 dermata alone, the remains of seventeen or eighteen species : 

 one elephant, six mastodons, three, or perhaps four, hippopo- 

 tami, as many rhinoceroses, an elasmotherium, one species 

 perhaps of the horse, and, at all events, one gigantic tapir. 



Of all these animals^ the horse is the only species that has 

 not been clearly proved to be absolutely foreign to the climates 

 where these remains are found. 



The mastodons constitute a genus by themselves now un- 

 known, but very much approximating to the elephant. The 

 elasmotherium is also most assuredly a separate and extinct 

 genus. All the others belong to genera now existing in the 

 torrid zone exclusively. Four of these genera, the elephant, 

 hippopotamus, rhinoceros, and horse, are found only in the 



