BLOOD-VASCULAR SYSTEM OF THE LORICATI II5 



rays and then follows along in front of the interhyal, but when 

 the preopercle is reached, instead of passing through a foramen 

 formed by the symplectic, hyomandibular, and preopercular 

 and anastomosing with the facialis-mandibularis artery to form 

 the mandibular artery as in Ophiodon, it bifurcates; the ventral 

 branch passes through the above mentioned foramen to become 

 the uiandihular artery (tig. 35, Man.A.) ; while the dorsal 

 branch passes along the inner surface of the preopercle, gives 

 off a rather large opercular artery, and terminates in the 

 pseudobranchial artery. 



Jugular Veins (tig. 35, J.V.). — The jugulars and their 

 branches are practically the same as in Ophiodon. 



The first pair of efibranchial arteries (figs. 35 and 36 ; Epbr. 

 A.(i)) unite in forming the dorsal aorta, and the second pair, 

 the coeliaco-mesentric ; there is an opening into the aorta from 

 the coeliaco-mesenteric artery, corresponding to the common 

 chamber of Ophiodon, but the subclavians arise separately from 

 the dorsal aorta, opposite the opening into the cceliaco-mesen- 

 teric. 



Subclavian arteries. — Each subclavian (fig. 36, Sub. A.) 

 after leaving the head kidney passes to the inner musculature 

 of the corresponding pectoral fin. Here it separates into the 

 subclavian artery proper, which is essentially the same as in 

 Ophiodon, and a hypobranchial artery. This vessel (fig. 36; 

 Hypobr.A.) passes ventrad a short distance, gives off a large 

 branch, designated as \\iQ posterior ventral artery {^g. 36; 

 Ven.A.(i^) which passes ventro-caudad, supplying the ventral fin 

 musculature and terminates in the right and left ventral fin 

 arteries. The main stem of the hypobranchial passes cephalad 

 and ventrad, and together with the corresponding vessel from 

 the opposite side anastomoses with the anterior ventral artery. 

 On the left side the hypobranchial artery has no posterior ventral 

 branch. The hypobranchial artery in Anoplopoma may not be 

 homologous with the similar named vessel in Ophiodon, which 

 is really a branch of the ventral artery and anastomoses with a 

 branch of the subclavian. 



Only one subclavian venous trunk (fig. 36 ; Sub.V.(2^) was 

 noticed. It arose from an external and an internal branch. 



