AETERIAL SYSTEM 



227 



a. The cardiac aorta is a direct continuation forwards 

 of the conus arteriosus. It is a median vessel, 

 lying beneath the floor of the mouth and pharynx, 

 and deeply placed in the muscles of the under 

 surface of the head. It is a little more than an 



F G. 39.— Scyllium canicula. Dissection of the arterial system from 

 the ventral surface. The floor of the mouth has been cut through 

 close to the median plane, and the light half turned outwards. 

 (c. H .H.) 



A, nostril. ATT, anilcle, B, rigbt orbit. BA, cat end of hindmost 

 branchial artery of the right side. B Al, first branchial artery of the left 

 side. B AS, fifth branchial artery of the leftside. ^ .BS, first efferent branchial 

 trunk, or epibranohial artery, of the right side. BF, fourth efEerent 

 branchial trunk, or epibranchial artery, of the right side. C, caiotid 

 artery. CA, oardiao aorta. D, the fifth or trigeminal nerre. DA, dorsal 

 aorta. S, external carotid artery. F, internal carotid artery at the point 

 where it enters the cranial cavity. G^, the hindmost of the efferent branchial 

 vessels. H, spiracle. I, efferent branchial loop of the first branchial cleft. 

 E, subclavian artery. Ml, first branchial cleft of the right side. M.6, fifth 

 branchial cleft of ths right side. IQ", longitudinal hypo-branchial artery. 

 O, cdnnecting-branch between the efferent branchial loops. SV, sinus^ 

 venosus. T, teeth, V, ventricle. 



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