293 Zoological Society. 



other quadrupeds, e. g. the larger Carnivora, is metamorphosed into 

 the yellow elastic tissue — tissu jaune — in the Aurochs, as in the 

 common Ox, and in a still greater degree in the Rhinoceros and 

 Elephant. By this change the abdominal muscles are proportionally 

 relieved or aided in the sustentation of the capacious and heavily- 

 laden digestive reservoirs. 



In the Aurochs, as in the other Ruminants, the disposition of the 

 omental sac upon the sternal aspect of the paunch, interposed between 

 it and the abdominal walls, makes it perform the office of a serous 

 articular sac, two smooth and lubricated surfaces — the inner ones of 

 the sac — being apposed to each other, and easily and freely gliding 

 on each other ; it is like a kind of great ' tunica vaginalis ' — facili- 

 tating the spiral peristaltic movements of the paunch, and by the 

 layer of fat tending to preserve the warmth of the paunch. 



The skeleton of the Aurochs has been well delineated by Bojanus, 

 in connection with an outline of the entire animal, and by Mr. George 

 Landseer separately. The general characters of the framework of this 

 rare species are very accurately rendered in both these figures. The 

 skeleton of the young male Aurochs showed the same characteristic 

 elevation of the spinous processes of the anterior dorsal vertebrae, 

 and the same characteristic number of ribs — fourteen pairs — which 

 are shown in the above-cited figures, and which repeated examina- 

 tion has established as constant peculiarities of the species. With 

 regard to the lengthened spines, I shall only remark on this inter- 

 esting morphological peculiarity, that it contributes to illustrate the 

 artificial nature of that view of the part commonly called rib, or ver- 

 tebral rib, as a bone or element of the skeleton, apart from or be- 

 longing to a distinct genus from the other vertebral elements. This 

 view originally arose from the contemplation of the proportions of 

 the ribs or pleurapophyses and spinous processes as they exist in Man. 

 A long and slender form is associated with the idea of a rib as an 

 essential character. In the Aurochs we see that the vertebral ele- 

 ment called neural spine is longer than the pleurapophysis in the 

 second and third dorsal vertebrae. But it is anchylosed to the other 

 vertebral elements, whilst the pleurapophyses retain their primitive 

 freedom, and the dorsal vertebrae are characterized as * articulating 

 with the ribs.' This, however, is a periodic, not an essential character. 

 At an early period of life the cervical vertebrae also articulate with 

 ribs, i. e. pleurapophyses ; but these become broad and remain short, 

 and coalesce with the centrums and diapophyses of their respective 

 vertebrae ; and the anthropotomist then calls them * transverse pro- 

 cesses,' and distinguishes them as being perforated, the foramen 

 being the space included between the centrum, the diapophysis, and 

 the pleurapophysis. 



Another remark is suggested by the skeleton of the Aurochs, 

 touching the true value of the character of its fourteenth pair of free 

 pleurapophyses. In the genus Bos proper there are only thirteen 

 pairs. In the American Bison there are ^ifeew pairs. According to 

 the artificial character in anatomy of the * dorsal vertebrae,' the above- 



