BLOOD-VASCULAR SYSTEM OF THE LORICATI EES 
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 Ophzodon, it bifurcates ; the ventral 
branch passes through the above mentioned foramen to become 
the mandibular artery (fig. 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 (fig. 35, J.V.).— The jugulars and their 
branches are practically the same as in Ophzodon. 
The first pair of epzbranchzal arteries (figs. 35 and 36; Epbr. 
A.) unite in forming the dorsal aorta, and the second pair, 
the cceliaco-mesentric; there is an opening into the aorta from 
the coeliaco-mesenteric artery, corresponding to the common 
chamber of Ophzodon, but the subclavians arise separately from 
the dorsal aorta, opposite the opening into the cceliaco-mesen- 
TenG: 
Subclavian artertes.— 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 the posterior ventral artery (fig. 363 
Ven.A.,,)) 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 Anxoflofoma 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...)) was 
noticed. It arose from an external and an internal branch. 
