Miscellaneous. 149 



of the Pampean deposits of South America is the abundance and 

 variety of the Edentata. 



The next most remarkable feature in the Niobrara fauna is its 

 marvellous richness in Solidungula, both genera and species. Making 

 allowance for doubles e/uplois, consequent upon the imperfection of 

 the materials, there will still remain a very large number of Equine 

 forms. The valley of the Missouri River, near the Rocky Mountains, 

 appears to have been the head-quarters of the Horses, during the 

 Pliocene period, very much after the manner in which India was the 

 head-quarters of the Proboscidea during the Miocene period. Ac- 

 cording to Dr. Leidy's determinations, it supported not less than 

 four generic or subgeneric types of Equus, namely, Hipparion, 2 sp. ; 

 Merychippus, 2 sp. ; Protohippus, 1 sp. ; Equus, 1 sp. ; and it is 

 further to be borne in mind that the subjacent Upper Miocene de- 

 posits of the same region have yielded two Anchitheroid forms, — 

 A. (Hypohippus) affinis and A. (Parahippus) cognatus ; while the 

 Lower Miocenes of the " Mauvaises Terres " contain Anchitherium 

 Bairdi, Leid. The post- Pliocene deposits of the littoral and central 

 States S. E. of the Mississippi have, in addition, furnished fossil 

 remnants which Dr. Leidy refers to Hipparion venustum, Leid., 

 Equus complicatus, Leid., and E. fraternus, Leid., the last two re- 

 presenting the post-Pliocene fossil species of Europe. The whole 

 make up a series of twelve North-American species, Anchitheroid 

 Hippotherian, and Equine proper. 



One statement is so unexpected that we quote it in the words of 

 the author. Dr. Leidy observed that, " among all the Mammalian re- 

 mains brought by Dr. Hayden from the Niobrara River, none were 

 more remarkable than those which he now exhibited. They belong 

 to an Equine animal which has the temporary teeth of Anchitherium 

 and the permanent teeth of Equus. In both these genera the per- 

 manent and deciduous teeth are alike ; but the new genus in early 

 life is an Anchitherium, and later in life a true Hot'se." The form 

 in question appears to be Merychippus mirabilis, Leid. 



The results yielded by the Niobrara fossil Pachydermata are equally 

 unexpected. Rhinoceros crassus, Leid., is described as a species 

 " which appears to have had almost the same size and formula of 

 dentition as the recent Indian Rhinoceros." In Mastodon mirificus, 

 belonging to the group Tetralophodon, " the form of the jaw is like 

 that of the existing Elephant of India ; a single tooth, the last molar, 

 occupies each side of it, and resembles the corresponding one of M. 

 angustidens of Europe or of M. Sivalensis of the Sivalik Hills of 

 India." Elephas imperator, Leid., was a colossal species, charac- 

 terized by molars nearly five inches broad, with unusually thick 

 plates, there being only eight bands of wear within a space of 

 seven inches, — a character which at once distinguishes this species 

 from the Mammoth of the United States, Elephas Americanus of 

 Leidy. 



Dr. Leidy's determinations will probably undergo considerable 

 modification before their final adoption by palaeontologists ; but the 

 single fact of an American Rhinoceros, in Pliocene deposits, approach- 



