112 



PISCES 



branchial arch (p. 258 and Figs. 72, 220). The dorsal portion of 

 the mandibular aortic arch (anterior carotid) having lost its 



artery; li.a, hyoid efferent vessel; up, nepauc veins; nt, IIBHIV, JI.K, uuavon 

 posterior efferent vessel ; s, spiracle ; v.a, ventral artery ; I-V, branchial slits. 



connection with the ventral aorta, acquires a new supply of blood 

 for the spiracular gill from the efferent vessel of the hyoid arch. 

 It passes thence across the floor of the orbit, through the lateral 



of 3 



Diagram of the branchial circulation of a Teleostean lish (modified from T. J. Parker), a. 6, 

 artery to air-bladde/- ; af 3-6, four afferent vessels from ventral aorta ; c.a, carotid artery ; c.c, 

 circulus cephalicus ; cl, coeliac artery ; d, ductus Cuvieri ; d.a, dorsal aorra ; ef s , efferent vessel 

 of first branchial arch ; ep, epibranohial artery ; h.a, hyoidean artery (afferent vessel of pseudo- 

 branch) ; hp, hepatic vein ; ht, heart ; mis, mesenteric artery ; o.a, ophthalmic artery (efferent 

 vessel of pseudobranch) ; p$, pseudobranch (hyoidean gill, possibly with spiracular gill) ; s, 

 position of spiracle (closed) ; v.a, ventral'artery ; I-V, live branchial slits.; 



carotid foramen, into the cranial cavity, where it joins its fellow 

 from the other side (front end of the original circulus cephalicus), 

 and gives off paired cerebral arteries and a median spinal artery. 



