Near the union of the first pair of efferent branchial arteries a small posterior vertebral artery arises from each, and runs anteriorly along the vertebral column.
Near the divisions of the common carotids two anterior vertebral arteries arise from these vessels and pass posteriorly, often anastomosing with the posterior vertebral arteries. These vertebral arteries are vestiges of the former anterior part of the dorsal aorta (compare with Eugaleus, in which the dorsal aorta sends forward two vessels which join the common carotids).
An oesophageal artery springs from the second efferent branchial, and passes back until it enters the wall of the oesophagus. It also gives off nutrient branches to the second, third, and fourth gill pouches. The nutrient artery of the first gill pouch arises directly from the first efferent branchial.
Near the point at which the fourth pair of efferent branchials join the aorta, two small subclavian arteries leave the aorta and pass into the pectoral fins. There is some variation in regard to the point of origin of these vessels; it may be either in front of or behind the junction of the fourth efferent branchials with the aorta.
The hypobranchial artery passes along the ventral ends of the gill pouches. It is either connected with the efferent branchial loops by short branches, or is formed, in part at least, by short vessels connecting these loops. The hypobranchials are important nutrient vessels, supplying the gill pouches and the muscles of the throat and the oesophagus by means of numerous small arteries; from the hypobranchials also arise small posterior coronary arteries which pass to the ventral and posterior walls of the pericardium and the sinus venosus, and larger anterior coronary arteries supplying the ventricle and conus arteriosus. The hypobranchials can frequently he followed along the dorsal side of the pericardium and then outward to junctions with the subclavian arteries.
The coeliac artery (coeliac axis) arises from the aorta just back of the subclavians. Passing posteriorly and ventrad close to the right side of the stomach and reaching the gastro-hepatic omentum, it divides into two branches, the gastro-hepatic and anterior intestinal arteries. The first gives off a small hepatic artery to the liver and a large gastric artery to the cardiac limb of the stomach. The anterior intestinal artery supplies the pyloric limb of the stomach, the pancreas, duodenum, and right side of the large intestine.
Small genital arteries, supplying the reproductive glands, arise from the coeliac near its origin. (In Eugaleus the genital arteries arise from the anterior and posterior mesenteric arteries.)
At about the middle of the abdominal cavity two arteries arise close together from the aorta. The anterior of the two is the anterior mesenteric artery; it passes to the left side of the large intestine and its branches anastomose more or less with those of the anterior intestinal artery. The posterior vessel is the lienogastric; it goes to the spleen, pancreas, and loop of the stomach.
The posterior mesenteric artery leaves the aorta a little distance back of the lienogastric and passes to the rectal gland, rectum, and cloaca.
Free the kidney from the body wall along its outer edge and turn it up so as to expose its dorsal surface. Observe the numerous parietal arteries (going to the body wall) and renal arteries (to the kidney), which spring from the dorsal aorta. Branches of the parietals also pass into the kidney.