The elasmobranch fishes (1934) The elasmobranch fishes elasmobranchfish03dani Year: 1934 178 THE ELASMOBRANCH FISHES BRANCHES OF EFFERENT-COLLECTOES HYPOBRANCHIAL ARTERIES The liypobraiichial arteries in Elasmobranchs form a most complex system of vessels in the ventral walls and floor of the pharyngeal area. In general the ventral ends of the different efferent-collector loops may be more or less com- pletely connected by a longitudinal vessel which, f ollo^^^ng Parker and Davis, I have termed in Heptanch us the lateral hypobranchial artery {, fig. 153). This vessel sometimes forms a c
The elasmobranch fishes (1934) The elasmobranch fishes elasmobranchfish03dani Year: 1934 178 THE ELASMOBRANCH FISHES BRANCHES OF EFFERENT-COLLECTOES HYPOBRANCHIAL ARTERIES The liypobraiichial arteries in Elasmobranchs form a most complex system of vessels in the ventral walls and floor of the pharyngeal area. In general the ventral ends of the different efferent-collector loops may be more or less com- pletely connected by a longitudinal vessel which, f ollo^^^ng Parker and Davis, I have termed in Heptanch us the lateral hypobranchial artery {, fig. 153). This vessel sometimes forms a con- tinuous ventral chain on each side from the first to the fourth effer- ent-collector loop (Mustelus, fig. 166). In Rata erinacea, and some- times in Carcharias littoralis, according to Parker and Davis (1899), the lateral hypobranchial may even include the fifth loop, but there is considerable irregu- larity about this. Whatever con- nections the loops may make with the lateral hypobranchials, how- ever, the tendency is to make them in the region of the second and third liranchial arches rather than from the first or last loops. In other forms the lateral hypo- branchial line is incomplete {Raja clavata), and in still others a lateral hypobranchial is absent {Dasijatis clipterura, fig. 167). Commissural arteries {cm.) may arise from the hypobranchial, at or pos- terior to the angles of the efferent-collector loops, and pass toward the mid- ventral line anterior to the third and fourth afferent arteries {Mustelns antarcticus, fig. 166a) ; or only a single one may be present as is usual for Squalus sucMii. The commissurals passing from the lateral hypobranchials medially may meet paired median hypobranchials as in Heptanchus macula- tus (fig. 153 and Hexanchus corinus, fig. 169). Some evidence of paired median vessels is also seen in Mustelns {, fig. 166). In certain forms the commis- sural may join an unpaired median hypobranchial as in Carcharias littoralis. The commi
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