SKELETON OF ARTIODACTYLA. 



473 



of the orbit and extends largely upon the face, at k, to join the 

 maxillary, h. The corresponding plate of the lacrymal is still 

 more extensive and here joins the nasally, leaving a small fissure 

 between those bones and the frontal, c. This very extensive bone 

 has a large superorbital fissure. The nasals are cleft at their 

 fore end. The premaxillary, g, has but a small or loose junction 

 with the nasals. The maxillary, h, is extensive, the antorbital 

 foramen, h\ perforates it above the first premolar. In Bison 

 europceus the horns arise in advance of the ridge formed by the 

 superoccipital bone, the parietals advancing to the upper surface 

 of the skull and being interposed between the frontal and super- 

 occipital. The Bison differs from the Buffalo {Bubalus) in the 

 greater breadth and convexity of the frontal, and in the much 

 greater extent of the orbital processes of that bone, which, with the 

 coextensive processes of the lacrymal and malar, form a prominent 

 cylinder. The nasals are relatively shorter and broader than in the 

 Ox (Bos) ; but the chief distinction between the Bison and the Ox 

 is seen in the shorter premaxillaries, which do not rise to join the 

 nasals : here, therefore, six bones enter into the formation of the 

 external nasal aperture, instead of four, as in Bos and Bubalus. 



The frontal sinuses extend into the horn-cores in all Bovines, 

 but not so in the majority of 

 Antelopes. In this rumi- 

 nant group, Aidth some ex- 

 ceptions, e. g. Aigoceros, 

 Lyroceros, Strepsiceros, Di- 

 cranoceros, the facial plate 

 of the lacrymal is impressed, 

 often deeply, by the antor- 

 bital cutaneous sac, com- 

 monly called ' lacrymal.' In 

 the Duykerbok ( Cephalo- 

 phus mergens), the parietals 

 are produced in an angular 

 form between the bases of the horn-cores, which spring as usual 

 from the frontals. In the Chickara ( Tetraceros) the frontal deve- 

 lopes two pairs of horn-cores : and this peculiarity was also mani- 

 fested by some gigantic Antelopes {Bramatheriiim and Swathe- 

 rium), now extinct, of the same continent (India) : in which, also, 

 the posterior horn-cores were ramified, as in the Prong-horn (Z)t- 

 cranoceros furcifer). The Sivathere was also remarkable for the 

 shortness of the facial part of the skull and the termination of the 

 nasals in a down-bent point, fig. 322. In the Duykerbok, Cha- 



322 



Frout view of the crauiuin of the Sivathcriur 



