1841.] Illustrations of the Genera of the Bovince. 451 



In Bibos, the same space (or posteal aspect of the skull) is of a 

 spheroidal shape, deeply indented about its centre by the temporal fossa?, 

 thus dividing it into two nearly equal hemispherical portions, viz., the 

 anterior and larger one formed entirely by the great intercornual crest, 

 and free from the insertions of nuchal muscles and ligaments, and the 

 posterior or truly occipital portion, occupied wholly by the insertions of 

 the neck muscles. The size of the intercornual crest in Bibos is so 

 great that the posteal aspect of the skull equals in extent the anteal 

 one, bounding the latter inferiorly by a line drawn across the face from 

 the centre of the orbits. Leaving the skulls, the following are the com- 

 parative differences in the trunk of these three animals. 



The great developement both in elevation and extent of the spinous 

 ridge in Bibos, at once distinguishes this animal from Bos and Bisonus. 

 In Bos the greatest elevation, much inferior in height, is confined to the 

 spinous process of one vertebra (the 3rd) whence the declension is 

 uniform to the 10th. In Bibos the extreme elevation is extended to three 

 of the spinous processes (the 3rd, 4th and 5th), and considerable elevation 

 prolonged to the 11th. In Bisonus again, which occupies a middle station 

 between Bos and Bibos in regard to extensive developement of the spines, 

 the extreme elevation, great in height as compared with Bos, is confined 

 to one spine, whence the declension is more sudden than in Bibos, but 

 less so than in Bos. These differences in the skeletons are manifested in 

 the living animal thus : in Bos the rise from the neck to the greatest 

 elevation of the spinous processes is most gradual, the highest point 

 being between the scapula, with declension thence gradual and uniform. 

 In Bibos the rise from the neck is more abrupt than in Bos, and the 

 declension very gradual until near the loins (at 10th Vertebra), whence to 

 level of loins very sndden indeed, giving the animal an appearance of 

 disproportioned smallness in its hinder extremities. In Bisonus the rise 

 from the neck is most abrupt, and confined as in Bos to the shoulders, or 

 rather entirely to the withers, whence the droop is more gradual and 

 uniform than in Bibos, but less so than in Bos. 



In detail these appearances arise from the following state of spinous 

 process. In Bos the first spinous process is only 2-3ds the length of the 

 2nd. In Bibos the 1st spine is to 2nd as 7 to 8. In Bisonus the 1st 

 spine (dorsal) is of extraordinary length and only perceptibly shorter 

 than 2nd one, which is the longest of all, whereas in Bos and Bibos the 

 3rd is the longest. 



Summary of Osteological Characters as noted above, 

 ^.—Dorsal Vertebrae and Ribs 13; Lumbar Vertebrae 6 ; Ribs laterally 

 bulging from the sixth pair giving great expansion of costal region ; 



3L 



