PEDIGREE OF MAMMALS. 277 



with the Anoplotheridae stamps the latter with tolerable 

 certainty as ruminants. 



Disregarding the camels, already mentioned as of 

 doubtful origin, the typical ruminants separate into the 

 deer-like and the horned. Through the hornless musk 

 animals, the deer are connected with the Tragulidae and 

 the older genera. The giraffes form a side branch. But 

 although the Helladotherium, nearly allied to the giraffe 

 and at one time inhabiting the Athenian territory in herds, 

 and the colossal Sivatherium, found in the spurs of the 

 Himalayas, afford some clue to the position of the 

 giraffes, so entirely isolated in the present world, the 

 details of their derivation still remain very obscure. 



From the antelopes to the closely allied — in fact, 

 scarcely separable — genera of goat and sheep, and 

 similarly to the oxen, the systematic as well as the palse- 

 ontological series, and likewise the ontogenetic phases, 

 present transitions undeniably evincing family relation- 

 ship. Besides the relations of the milk dentition of the 

 filial to the ancestral genera, which Riitimeyer has also 

 followed minutely, great interest attaches to the gradual 

 transformation of the skull, which reaches its extreme in 

 the oxen, and advances from the antelope and sheep, 

 through Ovibos, Bubalus (buffalo), Bison, to Bos (ox). 

 In the latter, the erect position of the frontal bone attains 

 its utmost grade, and this transformation of the skull of 

 the antelope is repeated in the calf. 



The usual classification of the Sirenia, or sea-cows, 

 with the Cetacea, was decidedly a systematic misconcep- 

 tion, arising from one-sided and, moreover, merely su- 

 perficial consideration of the locomotive organs. All 

 other characteristic indications — above all, the structure 



