XIl 



VASCULAR SYSTEi\I 



337 



right and left suprabranchial arteries behind, the characteristic 

 " circulus cephalious " of Teleosts is completed.'- From the 

 anterior part of the cephalic circle are derived two internal 

 carotid arteries^ 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. 



opk.a. 



l.cLa. 



FlQ. 199. — Branchial arterial system of the Cod (Gadus morrhua). Lateral view. 

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

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

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

 fins; hy.ps, spiracnlar pseudobranch ; in.c, internal carotid;'* l.d.a, left supra- 

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

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

 v.a, ventral aorta ; 1-5, hyobranohial 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 ^ 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 



' 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. 



' J. Miiller, XI. d. Bail, u. d. Grenzen d. Ganoiden, Berlin, 1846, p. 43 ; Eamsay 

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



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