2 VERTEBRATA. 



CLASS MAMMALIA. 



The fossil relics of this Class consist, for the most part, of single 

 and displaced bones, or groups of bones, the teeth, and the hard prod- 

 ucts of the skin. It is for this reason, as Cuvier long ago remarked, 

 that the determination of the remains of quadrupeds is beset with 

 more difficulties than that of other fossils; for while shells are often 

 found unbroken, and the skeletons or scaly coverings of fishes occur 

 more or less entire, the complete skeleton of a fossil mammal is rare. 



The earliest trace of mammals appears in the Upper Triassic — 

 the Microlestes, a very small insectivore, and probably a marsupial, 

 having been discovered in a bone-breccia at Diegerloch, Wirtem- 

 berg. Evidences of quadrupeds have been observed in American 

 strata of nearly the same antiquity, such as the tooth of the Dro- 

 niatheriimi, from North Carolina. The Jurassic of England has 

 furnished twenty species, probably all marsupials or non-placental, 

 for example, the Amphitheriuni, Amphilestes, Phascolotherium and 

 Stereognathtis, from the Stonesfield Slates ; and Spalacotherium, 

 TriGonodon and Plagiaulax, from the Lower Purbeck beds. As yet 

 the Cretaceous rocks have afforded no mammals, and a lapse of 

 time incalculably vast intervened between the Jurassic mammals 

 just mentioned and the Arctocyon and Coryphodon — the first ex- 

 amples of mammalian life in the Tertiary. From the Eocene to 

 the present day, an extensive and varied mammalian fauna has 

 existed, and left remains in the beds of ancient estuaries and rivers, 

 in the "Lake-beds" of the Rocky Mountain region, in peat bogs, marl 

 pits, and in caves, which served as lairs for predaceons species, and 

 as charnel-houses to their prey. Under the hand of Cuvier the 

 Eocene specimens became the opening chapter to the great volume 

 of Palreontological Science. 



ORDER PRIMATES. 



SUBORDER BIMANA. 



FAMILY HOMINID^. 



This family, which justly stands at the head of animated Nature, 

 includes only one genus — Homo, — and but one well determined 

 species — sap)iens, or Man. He is the only animal truly bimanous 

 and biped. In him the vertebrate type, which began during the 

 Palaeozoic age in the horizontal fish, finally becomes erect. He is 

 the only living mammal having no diastema in the dental series of 

 the jaw. But his most important anatomical feature is the great 

 size and complexity of the brain; and his distinguishing zoological 

 characteristic is the possession of speech. 



