CAVITIES OF HEART 



has remained. This fact, therefore, shows that the mammal 

 cannot have been derived from a bird-like ancestor, but that 



FIG. 43. Lepus cunicnlus. Ven- 

 tral view of the vascular sys- 

 tem. The heart is somewhat 

 displaced towards the left of 

 the subject ; the arteries of 

 the right and the veins of the 

 left side are in great measure 

 removed, a.epg, internal mam- 

 mary artery ; /, anterior facial 

 vein ; a.m, anterior mesenteric 

 artery ; a.ph, anterior phrenic 

 vein ; az.v, azygos vein ; br, 

 l>rachial artery ; c.il.a, common 

 iliac artery ; c.il.v, common 

 iliac vein ; cce, coeliac artery ; 

 d.ao, dorsal aorta : e.c, external 

 carotid artery ; e.il,a, external 

 iliac artery ; e.ti.v, external 

 iliac vein ; e.ju, external jugu- 

 lar vein ; fm.a, femoral artery ; 

 fm.r, femoral vein ; h.v, hepatic 

 veins ; i.c, internal carotid 

 artery ; i.cs, intercostal vessels ; 

 i.il.a, internal iliac artery ; i.il.v, 

 internal iliac vein ; i.ju, internal 

 jugular vein ; i.l, iliolumbar 

 artery and vein ; in, innomin- 

 ate artery ; l.au, left auricle ; 

 l.e.c, left common carotid ar- 

 tery ; l.pr.c, left pre-caval vein ; 

 /.?', left ventricle ; m.sc, median 

 sacral artery ; p.a, pulmonary 

 artery; p.epg, epigastric a rtery 

 and vein ; p.f, posterior facial 

 vein ; p.m, posterior meseu- 

 teric artery ; p.ph, posterior 

 phrenic veins ; pt.c, jiost-caval 

 vein ; p.v, pulmonary vein ; r, 

 renal artery and vein ; r.av, 

 right auricle ; r.c.c, right com- 

 mon carotid artery ; r.prc, right 

 pre-caval vein ; r.v, right ven- 

 tricle ; s.cl.a, right sulxilavian 

 artery ; s.rt.i; subclavian vein ; 

 s]>m, spermatic artery : s.vs, 

 vesical artery ; ut, uterine artery 

 and vein ; vr, vertebral artery. 

 (From Parker's Zootomy.) 



both must have independently come from an ancestor with 

 both halves of the aortic arch present, of which one half 

 has disappeared in one group, and the other half in the 

 other. It is an interesting fact, too, to notice that the four 



