474 THE POPULAR SCIENCE MONTHLY. 



have an uneven number of toes — as the horse with one toe, and the 

 rhinoceros with three — and the Artiodactyles, or the ungulates with 

 an even number of toes — as the hippopotamus with four toes, and the 

 hog with its two functional toes. Now, of these fossil ungulates it is 

 remarkable that the expedition has brought home from the Miocene 

 twenty Perissodactyles, and the same number of Artiodactyles ; and 

 from the Pliocene nine Perissodactyles, of which four are new, and 

 six Artiodactyles, of which three are new ; thus making fifty-three 

 ungulates. Of these there are several horses, and all of them, includ- 

 ing Anchitherium and Protohippus, have three toes to each foot. 

 These cloven-footed beasts were some of them strange, comprehensive 

 types, possessing in the same individual structural resemblances to both 

 swine and deer ; " like the latter, these had no horns ; they were 

 about as large as sheep. Others were about the size of gray squirrels, 

 being the smallest of this class of animals ever discovered " (A?nerican 

 Naturalist). Indeed, an important paleontological result has been 

 Prof. Cope's determination of the correct relationship of five species 

 (three new, and one new genus, Hypertragidus) to the musk family. 

 The general reader should perhaps be told that the order Uhgulata, 

 or hoofed quadrupeds, really absorbs three of the orders in the older 

 classifications, namely, the Pachydermata, the Solidungula, and the 

 Huminantia. This mentioned, we would say, with no irreverence, 

 that in the Colorado fauna of Tertiary times Nature seemed to indulge, 

 as respects the animals of this order, in the most eccentric extremes 

 of structure, both as to form and size ; for some of these hoof-footed 

 ones are scarcely larger than a squirrel, while some are as large as the 

 elephant ; and there is a seeming oddity of structure. Though a fact 

 before every one's eyes, yet many are not aware of its existence, viz., 

 that the ox and cow have no teeth in the front part of the upper jaw. 

 When this animal grazes, the tongue makes a curl, or twist, and pulls 

 in the grass, then the lower front teeth are made to meet the firm pad 

 of the front part of the upper jaw, and the grass is then severed. 

 Such is~ the mode common to the ruminating animals, that is, those 

 which chew the cud. Now, in the natural group Ruminantia, comes 

 a sub-group, the Camelidm, which includes the camels and the llamas. 

 The dentition of these animals is very aberrant. The upper incisors 

 are not entirely wanting, " there being two canine-like upper incisors, 

 and upper canines as well." In the Pliocene strata of Colorado are 

 found the remains of two species of camels, of enormous size, and 

 which, strange to say, are furnished with complete upper incisors, or 

 front-teeth. These ancient camels, then, did not graze like the ox, 

 but like the horse. 



And, among these hoofed creatures, the Phinocerotidce are repre- 

 sented by three genera. Two of them belong to the Miocene, and the 

 third, the last discovered, to the Pliocene. This is the new genus 

 Aplxelops, a monster of immense proportions. The other two genera 



