252 



DIPNOI 



Dipneumones pass directly, without breaking up into capillaries, to 

 the aorta, as in terrestrial vertebrates. In Ceratodus, but not in the 



-sc. 



Diagram of the venous system of Ccmtodiw Forsteri, dorsal view. (After Spencer.) a, atrium ; 

 a?>, anterior abdominal vein ; br, branchial vein ; c, conus; c.v, caudal vein ; h.p, hepatic portal 

 vein ; i.j, inferior jugular vein ; il, iliac vein ; k, kidney ; I, liver ; l.c, lateral cutaneous vein ; 

 Lp.c, left posterior cardinal ; p, pulmonary vein ; pt.v, posterior vein from body-wall ; p.v, pelvic 

 vein ; r.p, renal portal vein ; r.p.c, right posterior cardinal ; *c, subclavian vein sj, jugular 

 vein ; t, testis ; v ventricle ; v.c, vena cava. 



Dipneumones, the hyoidean hemibranch is a pseudobranch, receiving 

 blood only from the efferent system (Spencer, Parker, Figs 220-21). 

 Three chief points of interest are found in the venous system 

 (Figs. 222-4). Firstly, the pulmonary blood is returned directly to 

 the heart by a vein passing to the left side of the sinus venosus, as 



