XII 



VASCULAR SYSTEM 



337 



right and left suprabranchial arteries behind, the characteristic 

 " circulus cephalicus " of Teleosts is completed. 1 From the 

 anterior part of the cephalic circle are derived two internal 

 carotid arteries 2 for the brain, and also a pair of orbito-nasal 

 arteries for the eye- muscles and the nasal sacs, while more 

 posteriorly an external carotid has its origin from each supra- 

 branchial artery. 



cpfi.a. 



l.cLa. 



sb.a. 



in.c. 



of. d.a. 



Hyb.a,. 



(/.a,. 



FIG. 199. Branchial arterial system of the Cod (Gadus morrkua). Lateral view. 

 af.b.a, First afferent branchial artery ; cl.a, coeliac artery ; d.a, median dorsal 

 aorta ; ef.b.a, first efferent branchial artery ; ex.c, external carotid ; H, heart ; 

 hy.a, hyoidean artery ; Hy.b.a, hypobranchial artery for the heart and pelvic 

 fins; hy.ps, spiracular pseudobranch ; in.c, internal carotid; 2 1. d.a, left supra- 

 branchial artery ; m.a, mesenteric artery ; on, orbito-nasal artery ; oph.a, 

 ophthalmic artery ; r.cl.a, right suprabranchial artery ; sb.a, subclavian artery ; 

 v.a, ventral aorta ; 1-5, hyobranchial and succeeding gill-clefts. (Altered from T. 

 Jeffery Parker.) 



(3) In most Teleostomi the air-bladder is supplied with blood 

 by branches of the coeliac artery, with the addition of small 

 branches arising directly from the dorsal aorta. Polypterus and 

 Amia 3 are, however, exceptional, inasmuch as the arteries for the 

 air-bladder are derived from the last or fourth pair of efferent 

 branchial vessels, and in this respect, but not in the destination 



1 For the relations of the efferent branchial vessels to the cephalic circle and 

 the median dorsal aorta in different Teleosts, see Ridewood, P.Z.S. 1899, p. 939. 



2 Only one of the two internal carotid arteries is shown in Fig. 199. 



3 J. Miiller, V. d. Bau u. d. Grenzen d. Ganoiden, Berlin, 1846, p. 43 ; Ramsay 

 "Wright, Staiidard Nat. Hist. iii. pp. 48, 49. 



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