1877. ] - Recent Literature. T51 
greater part of the remains on which this report is based were collected 
by the author himself, who thus had the opportunity of becoming 
familiar with their stratigraphical relations. 
In discussing the character of the great Eocene plateau of New Mex- 
ico, first explored by Professor Cope in 1874, it is claimed that the Ter- 
tiary mammalian fauna originated through a migration from the south- 
ward, replacing the Mesozoic type of Saurians which had until then 
occupied the field. “ New Mexico,” he concludes, “ was then no doubt 
the source from which the fauna of Wyoming was derived, and the exten- 
sion of the Wahsatch [or Green River] fauna probably proved fatal to 
the latest representatives on the American continent of the dinosaurian 
and other reptilian forms of Mesozoic time.” 
The work before us is divided into three chapters: the first is đe- 
voted to the Fossils of the Mesozoic Periods and the Geology of the 
Mesozoic and Tertiary Beds ; the second to the Fossils of the Eocene 
Period ; and the third to the Fossils of the Loup Fork Epoch. The 
Mesozoic vertebrata described embrace a single species of fish allied to 
the Mugillide, a large crocodilian, and a large, “ probably terrestrial ” 
animal, “ with powerful fore and hind limbs subequally developed,” ca 
Dystrophæus viemale, of doubtful class affinities. The Eocene types in- 
clude several forms known also from the Cretaceous and Tertiary, and 
the Lepidostoid genus Clastes, known thus far only from the Eocene of 
the Rocky Mountains. The reptiles are more numerously represented, 
and embrace turtles, crocodilians, and ophidians. Of the six genera of 
turtles three (7rionyx, Dermatemys, and Emys) still exist. The several 
species of crocodiles are referred (some of them doubtfully) to the exist- 
ing genus Crocodilus. The only bird described (Diatryma gigantea) was 
of large size, the single tarso-metatarsal bone, by which it is thus far 
known, having a breadth at its proximal end “nearly twice the diameter 
of that of the ostrich. Its discovery introduces this group of birds to 
the known faune of North America, recent and extinct, and demon- 
strates that this continent has not been destitute of the gigantic forms of 
birds now confined to the southern hemisphere faunz.” It is considered 
allied to Gastornis Hébert of the Eocene of France. The mammalia 
of this period are numerous, amounting to fifty-four species. Of these, 
ten are referred to the order Perissodactyla, eight to the order “ Ambly- 
poda,’ thirty to his new order “ Bunotheria,” and three to the order 
Rodentia. Space will not permit of more than a brief notice of these 
= groups, the affinities and characteristics of which, and their various sub- 
divisions, are discussed in detail. The Bunotheria were abundantly repre- 
sented during the North American Eocene, during which period they , 
“fulfilled the functions of the existing Carnivora.” While they agree 
- quite nearly in structure among themselves, they differ in important par- 
ticulars from the true Carnivora. They are described as varying from 
the size of a weasel to that of a jaguar. Some of the puzzling forms 
