THE FROG: VISCERA AND VASCULAR SYSTEM 57 



Blood Vessels. 



CU 



From the truncus arteriosus there arise on each side three 

 arteries, which are for some distance bound together, so 

 that they seem to 



be a 



single 

 vessel. The hinder- 

 most of these is 

 the pulmocutaneous 

 arch, the middle 

 the systemic arch, 

 the foremost the 

 carotid arch. After 

 separating, the 

 three arches con- 

 tinue to run out- 

 wards, diverging as 

 they go. The pul- 

 mocutaneous arch 

 divides into the 

 pulmonary artery 

 for the lung and 

 the cutaneous artery 

 for the skin. The 

 carotid arch gives 

 off forwards a lin- 

 gual artery to the 

 muscles of the 

 tongue and hyoid, 

 and then becomes 

 the common carotid 

 artery which bears Fig. 30.— A diagram of the arterial system of 

 a round swelling the frog, seen from the ventral side. — 



due to the fact that From Thomson. 



it here breaks UD ^ r '> Subclavian or brachial; c, common carotid; a.m., 



. * coeliaco-mesenteric ; cu. t cutaneous artery ; h. y 



intO a number Of hasmorrhoidal ; il., common iliacs ; £., left kidney; 



small vpscpIs whirVi l -< Ungual artery; A, pulmonary; *-., renal; s., 



small vGaacio w 1111,11 systemic arch; t., right testis; 71., occipito-verte- 



reunite. ThisSWel- bral. The right spermatic artery is shown hut not 



, • . , . . 7 lettered. The posterior mesenteric is not shown. 



ling is the carotid 



labyrinth, often inappropriately called the carotid gland. 

 The friction of the blood against the large surface pro- 

 vided by its numerous small vessels is the cause of the 



