. The elasmobranch fishes. Chondrichthyes. THE ELASMOBRANCH FISHES 163 branchial artery {, fig. 153); or the lateral liypobranchial vessels may arise from tlie ventral parts of the eiferent-colleetor loops; or again a lateral hypobranchial segment may be incomplete between certain of the commis- surals. Jnst before reaching the midventral line the commissurals of each side form a larger longitudinal vessel, the median hypobranchial {),i\ right and left median hypobranchials being connected by several small connectives {en.) which may or may not unite right and left pairs of commi
. The elasmobranch fishes. Chondrichthyes. THE ELASMOBRANCH FISHES 163 branchial artery {, fig. 153); or the lateral liypobranchial vessels may arise from tlie ventral parts of the eiferent-colleetor loops; or again a lateral hypobranchial segment may be incomplete between certain of the commis- surals. Jnst before reaching the midventral line the commissurals of each side form a larger longitudinal vessel, the median hypobranchial {),i\ right and left median hypobranchials being connected by several small connectives {en.) which may or may not unite right and left pairs of commissurals. The tAvo median hypobranchial trunks are continued posteriorly above the peri-. Fig. 152. Arterial branches of first efferent-collector, Heptanchus macuJatus. (Marie Weldt, orig.) , anterior cerebral; , arteria spinalis; }, first branchial efferent; }, paired dorsal aorta; , dorsal aorta; , hyoidean efferent; , internal carotid; , median cerebral; ns., nasal artery; , ophthalmica magna; or., orbital artery; , posterior cerebral; ps., pseudobranchial artery; , ramus anastomoticus; rs., rostral artery; sg., segmental artery. cardial roof as the two large pericardial arteries (^^c). The pericardials may be of essentially the same size or the right one may be the better developed (see fig. 154, ). The epigastric artery (epg., fig. 154), which supplies branches to the oesophagus and the stomach, is a branch off of the pericardial or is the direct continuation of the right one. A large vessel is given off from the median hypobranchial between commis- sures two and three, or three and four, which passes to the midventral line and joins a similar artery from the opposite side. This united trunk extends poste- riorly, and at the sixth commissural divides into the right and left coracoid arteries (), which join the subclavian arteries. Similarly, near the sixth commissural, an artery arises from the median hypobranchial on ea
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