1887.] 397 [Cope. 



as genera and named accordingly. So far as concerns the skeleton, 

 further subdivisions than those indicated in the above table do not 

 appear to exist, and none have been pointed out. The divisions proposed 

 appear to be rather those of one extensive genus. The modifications of 

 tlie skull have reference to the position of the horns. These are processes 

 of the frontal bones, and are placed at points from above the eye to the 

 posterior angle of the facial plane of the skull. In the latter case this 

 angle approaches very near to the supraoccipital crest or inion, and the 

 parietal bone is reduced to an exceedingly narrow band between the 

 frontal and occipital bones (Riitimeyer).* Forms with anterior horns and 

 well-developed parietal bone are Ocis gazella and Tetrarerus quadricornis , 

 "while the Ocis gnu displays the parietal extremely reduced, and become 

 chiefly lateral in position. As regards the forms of the horns themselves, 

 they present no important differences, but are angular and revolute in the 

 section Ovis, and cylindric in the division Antilope. In the latter they 

 vary in direction from straight to spiral or curved in different directions. 

 Within the genus Ovis the end of the muzzle is naked or hairy, the latter 

 in the typical forms and in those inhabiting northern and alpine localities 

 generally. Those species that inhabit grassy or desert plains have the end 

 of the nose naked. 



Within the genus Bos modifications are observed parallel to those in the 

 genus Ovis. The frontal bones with the horn processes are produced 

 more and more posteriorly until the parietal bones are reduced to a narrow 

 band across the posterior part of the skull. The bisons have the horns 

 most anterior ; then follow the buffalos, and the extreme is reached in the 

 true oxen, of which the domesticated animal is the type. 



The following'table will give an idea of the phylogeuy of the Bovidse : 



Ssega Bos Tetracerus Sivatheriinne CervMae 



Ovis Antilocapra Dicrocerus 



. Cosoryx Blastomeryx 



Palieomeryx 

 The hornless Palteomeryx has given origin to the horned BoiJidea ; on 

 the one hand to the brachyodont (Blastomeryx, etc.), and on the other to 

 the hypsodonts (Cosoryx, etc.). A cornification of the integument in a 

 fork horned Cosoryx produced Antilocapra, while the same process in a 

 simple-horned Cosoryx produced Ovis. The development of this tj'^pe 

 has undergone the three principal modifications indicated by the three 

 genera which succeed upwards. In Sajga an extraordinary development 

 of the muzzle takes place, which causes a change in the relations of the 

 nasal bones. In Tetracerus another pair of horns is developed in front of 



*Die Kinder der Tertiiir-Epoclie ; Abli. Scliweiz. Pal. Gess., v, 1878. 



