112 



PISCES 



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

 the mandibular aortic arch (anterior carotid) having lost its 



af* 



lit. 



FIG. 71. 



Diagram of the branchial circulation of an Elasmobranch fish (modified from T. J. Parker). 

 .o, median anterior prolongation of aorta; n.c, anterior carotid, efferent vessel of spiracular 

 gill (pseudobranch) ; a.ef, efferent vessel from last hemibranch ; a./, anterior efferent vessel ; 

 0/2.6, five afferent vessels from ventral aorta ; af.a, afferent artery of spiracular gill ; c, conus 

 leading to ventral aorta ; d, coeliac artery ; d, ductus Cuvieri ; d.a, dorsal aorta ; ef, epibranchial 

 artery ; h.a, hyoid efferent vessel ; hp, hepatic veins ; ht, heart ; p.c, posterior carotid ; p.ef, 

 posterior efferent vessel ; s, spiracle ; v.a, ventral artery ; bV, 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 



ca. 



oa: 



Jit. 



Diagram of the branchial circulation of a Teleostean fish (modified from T. J. Parker). a.Z>, 

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

 circulus cephalicus ; d, coeliac artery ; d, ductus Cuvieri ; d.a, dorsal aorta ; ?/3, efferent vessel 

 of first branchial arch ; ep, epibranchial 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) ; ps, pseudobranch (hyoidean gill, possibly with spiracular gill) ; s, 

 position of spiracle (closed) ; v.a, ventral artery ; I-V, five 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. 



