THE VASCULAR SYSTEM, 



141 



branches, which run straight outwards in the floor of the 

 pharynx. Each of these branches divides, after a short course, 

 into three vessels, and the hindmost vessel again into two. In 

 this way the four afferent branchial vessels AF^, AF^, AF^, AF^, of 

 the first, second, third and fourth branchial arches respectively 

 are formed. 



GM AB 



EF.3 Efvi CP 



VD AF.. RB RA RV Af^a RT 



Fig. 34. A diagrammatic figure of the head and neck of a 12 mm. tad- 

 pole from the right side, to show the heart and branchial vessels. The 

 gills and the gill capillaries are not represented, x 35. 



A, dorsal aorta : AB, basilar artery : AFi, AF2, AF4, afi'erent branchial 

 vessels of first, second, and fourth branchial arches : AL, lingual artery : 

 AP, pulmonary artery : AR, anterior cerebral artery : AS, posterior 

 palatine artery : AT, anterior palatine artery : AU, cutaneous artery : 

 AY, pharyngeal artery : CA, anterior commissural vessel : CG, carotid 

 gland : CP, posterior commissural vessel : EFi, EF2, EF3, EF4, efferent 

 branchial vessels of first, second, third, and fourth branchial arches : 

 GM, glomerulus: RA, right auricle: RB, left auricle: RT, truncus 

 arteriosus : RV, ventricle : VD, Cuvierian vein : VH, hepatic vein : 

 VI, posterior vena cava : VP, pulmonary vein. 



Each afferent vessel runs outwards and upwards in its own 

 arch. The efferent branchial vessels lie immediately in front 

 of the corresponding afferent vessels, with which they are 



