1886.] On the Blood-vessels of Mustelus antarcticus. 473 



The dorsal portion of the hyoidean aortic arch (Jiyoidean epihranchial 

 artery) is represented by the proximal portion of the posterior carotid 

 artery and by a delicate vessel proceeding backwards and inwards 

 from it, which, uniting with its fellow of the opposite side, forms a 

 slender median longitudinal trunk, the rudimentary anterior (inter- 

 hyoidean) portion of the dorsal aorta. 



It is suggested that the original mandibular aortic arch is repre- 

 sented partly by the pseudobranchial artery which supplies the pseudo- 

 branch (mandibular gill) and partly by the mandibular artery, which 

 springs from the ventral end of, and takes a course parallel with, the 

 first efferent branchial artery. 



A classified list of the peripheral arteries is given, dividing them 

 into (a) those arising from the efferent branchial arteries (aortic 

 arches) ; and (b) those arising from the dorsal aorta. 



The anterior carotid artery, formed by the union of the efferent 

 arterioles of the pseudobranch, supplies the brain and eye, and 

 anastomoses with the posterior carotid. 



The posterior carotid supplies the orbit, snout, and jaws. 



The mandibular artery supplies the angle of the mouth and the 

 submental region, and gives off nutrient vessels to the hyoidean 

 demibranch. 



The subclavian artery — the first vessel springing from the dorsal 

 aorta — divides into a brachial artery for the pectoral fin, and a hypo- 

 brancliial artery, which unites with its fellow, anastomoses with the 

 whole series of efferent branchial arteries, and gives off coronary, 

 pericardial, and nutrient branchial arteries. 



The splanchnic arteries consist of a cceliaco-mesenteric, a lieno- 

 gastric, and anterior and posterior spermatico-mesenteric arteries ; 

 the two latter also supply the gonad. 



There is only a general correspondence between the splanchnic 

 arteries and veins of different elasmobranch genera. 



An embryological classification of the veins is given : they are 

 divided into the following groups : (a) system of the subintestinal 

 vein, consisting of renal portal, and hepatic portal sections ; (b) system 

 of the cardinal veins ; (c) system of the lateral veins ; (d) system of 

 the coronary veins ; and (e) system of the cutaneous veins. 



The caudal vein, on emerging from the haemal canal, divides into 

 right and left renal portal veins, which send branches into the kidneys 

 and receive the posterior spinal and oviducal veins. 



There is a large intra-intestinal vein enclosed in the free edge 

 of the spiral valve, and continued directly into the hepatic portal 

 vein. 



There are two hepatic veins, opening into a large hepatic sinus, 

 which communicates by two small apertures with the sinus venosus. 

 The paired precaval sinuses receive the jugular, the inferior jugular, 



