A further resemblance to the Amphibia is to be found in the presence of an anterior abdominal vein. After leaving the pelvic {326}limb each femoral vein divides into two branches; one of these forms a renal portal vein as previously described; the other, which may rightly be termed a pelvic vein (_pv.v_), unites with its fellow to form a median anterior abdominal vein (_a.ab_). Pursuing its course forwards in the ventral abdominal wall, the vein eventually reaches the heart and opens into the sinus venosus. The direct connexion of the anterior abdominal vein with the heart is yet another example of the retention in the adult _Neoceratodus_ of a transitory embryonic feature in the developing Amphibian.[370] [Illustration: FIG. 192.—Venous system of _Protopterus_. _a_, Auricle; _a.c_, anterior cardinal; _an.v_, anastomotic veins; _c_, intestine; _f.v_, femoral or iliac vein; _g.b_, gall-bladder; _h.p.v_, hepatic portal vein; _i.j.v_, inferior jugular; _ov.v_, ovarian veins; _p_, pericardium; _p.c.v_, left posterior cardinal; _p.v′_, parietal or segmental veins; _s_, stomach; _sb.v_, subclavian. Other reference letters as in Fig. 191. (From Newton Parker.)] As in other Fishes, the blood from the head is conveyed to the Cuvierian ducts by an anterior cardinal and an inferior jugular on each side. There are no lateral veins, the blood from the pelvic fins flowing into the renal portal system or into the anterior abdominal vein, and that from the pectoral fin through subscapular and brachial veins into the Cuvierian ducts. Lateral cutaneous veins are, however, present; and, as in Elasmobranchs (e.g. _Mustelus antarcticus_), anastomose anteriorly with the subscapular vein and behind with the caudal vein. {327}Less is known of the venous system of _Protopterus_,[371] but it is certain, nevertheless, that it presents a more advanced grade of evolution than in _Neoceratodus_, and, except for the doubt as to the existence of an anterior abdominal vein, it is essentially similar to that of a Urodele Amphibian in which the right posterior cardinal vein has aborted.