v:u 



H. 



v.u 



a.c.u 



v.u 



*V li. 



ce ce. 



a.c.Vr 



Fig. 190. — Development of venous system of Lepidosiren. (After Robertson, 1913.) 



A-F, ventral portion of venous system as viewed 'from the iventral side ; b-e, dorsal portion as 

 viewed from the dorsal side. A, stage 24 ; B, 25 ; C, 30 ; D, 32 ; E, 35 ; F, young adult ; b, 27-30 ; c, 

 30-31 ; d, 31 + ; e, young adult, a.c.v, anterior cardinal vein ; ce' and ce", anterior and posterior cere- 

 bral veins; d.C, duct of Cuvier; S, heart; i.j, inferior jugular; ir.v, inter-renal vein; l.c, lateral 

 cephalic vein ; l.v, lateral cutaneous vein ; li, liver ; p, pulmonary vein ; pa, vein from pancreas ; p.c.v, 

 posterior cardinal ; %>l, pelvic vein ; p.v.c, posterior vena cava ; r, rectal vein ; s, subclavian vein ; s.i.v 

 and s.i.v", subintestinal vein ; s.v, sinus venosus ; sp, splenic vein ; v, vestigial front end of right 

 posterior cardinal ; v.v, vitelline veins ; * points at which vessels become discontinuous. 



