ARTERIES OF MAMMALIA. 



535 



the aorta sends off a large common trunk, a, b (the ' ante- 

 rior aorta' of Veterinarians), which divides into two brachio- 

 carotids, each subdividing after a longer or shorter course into 

 the brachial d or d' 9 and the carotid c or c' of its respective 

 side : the vertebral artery, v 9 is given off by the brachial. The 

 arch of the aorta, diminished after dismissing b, is the { posterior 

 aorta ' of Hippotomy ; and, indeed, in this variety the trunk of 

 the arterial system appears to bifurcate shortly after its origin. 

 In the Rhinoceros the ' anterior aorta ' sends off the two internal 

 thoracics, the two brachials, and a common trunk subdividing into 

 the two carotids. 1 In Auchenia, fig. 419, b, the left brachial, d' 9 



Origins of arteries from aortic arch in Mammals. 

 A, Ox. B, Lama, c, Giraffe, d, Lion, a, Otter, f, Gibbon, o, Hedgehog, h, Man. I. Dugong. 



comes off close to, but distinct from, the innominate trunk, b ; 

 which, after dismissing the right brachial, d, sends onward a long 

 common bi-carotid trunk, dividing into c, c'. A similar arrange- 

 ment obtains in the Giraffe, 2 ib. c ; but the bi-carotid is still 

 longer before its division, and the left internal thoracic, v' 9 has a 

 distinct origin from the aorta, «, beyond that of the left brachial, d'. 

 In Suidce a longish innominata gives off the right brachial and 

 both carotids, almost at the same terminal point : the left brachial 

 rises close to the innominata. In the Elephant I found a short 

 innominata giving off the right brachial and both carotids, the 



v". p. 47. 



2 xcvm". p. 229. 



