3i8 



COMPARATIVE MORPHOLOGY OF VERTEBRATES 



being the development of the postcava, the rudimentary right postcardinal, and 

 the fact that the hepatic veins empty into the sinus venosus and not into the 

 postcava as in the amphibia (fig. 339JV 



Fig. 337. — Anterior arterial vessels of the tile fish {Lopholalilus), after Silvester, a, 

 atrium; ab, to air bladder; am, to angle of mouth; c, cceliac axis; d, dorsal arteries; da, 

 dorsal aorta; ec, external carotid; g, genital artery; gs, gastrosplenic; h, hyoid artery; ha, 

 hepatic; /, Ungual; Ig, left gastric; m, mesenteric; mh, middle hypobranchiaJ; 0, ophthal- 

 mic; pa, parietal; po, postorbital; ps, pseudobranch; rg, right genital; so, supraorbital; 

 V, ventricle; va, ventral aorta. 



AMPHIBIA. — In the anaghibia the heart is carried back into th£_trnnk, to 

 ^n extent not found in_any of _the fishes, and it shows another advance in develop- 

 ment in having the atria in front of the ventricle, a condition which reappears 



Fig. 338. — Anterior venous system and heart of Lopholalilus, after Silvester, a, 

 auricle; ab, veins from air bladder; b, bulbus; bv, brachial vein; c, cerebral vein; cd, 

 Cuvierian duct; cv, caudal vein; d, dorsal branches of parietal veins; /, facial vein; g, 

 gastric veins; hp, hepatic portal; hv, hepatic veins; i, outline of mesonephros; ij, 

 inferior jugular; in, is, veins from intestine and spleen;;, jugular; /, liver; m, mesenteric 

 vein; pe, postcardinal; pd, postcloacal; per, peritoneal; ph, pharyngeal; /»o, postorbital; 

 re, anterior revehentes; s, sinus venosus; si, veins from stomach and intestine; th, thy- 

 reoid; tm, thymus; v, ventricle; va, ventral aorta; vf, vein from ventral fin. 



in all of the higher vertebrates. The division of the primitive atrium by a sep- 

 tum atriorum is carried farther than in the dipnoi. This septum is fenestrated 

 in the urodeles and gymnophiona, entire in the anura, but in none does it extend 



