172 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
probably also true of Mustelus (Parker, ’87, p. 720), but in Selache 
(Pavesi, ’74, p. 62) and Acanthias (Rose, ’90, p. 84) the veins are 
described as uniting and entering the sinus by a single opening. 
Right and left systems have been identified in Mustelus (Parker, 
’87, p. 720) and in Selache (Pavesi, ’74, p. 68), and in the latter, 
as in Carcharias, the left system is more fully developed than the 
right. 
In Raja erinacea the right coronary vein is represented by two 
vessels (PL 3 , fig. 8, vn. cor. dx.), which have separate openings 
into the venous sinus, one of which lies more to the right than the 
other. The vein on the extreme right has two principal branches, 
the first one to the dorsal surface of the cone and the second to the 
ventral surface of this organ and of the ventricle (Fig. 11, vn. cor. 
dx.). This second branch passes through the right side of the 
groove which separates ventricle from cone. The vein to the left 
also has two principal branches, one of which extends over the 
dorsal side of the cone (Fig. 8) and the other passes over the ven¬ 
tricle to the left of the cone to be distributed finally to the ventral 
face of the ventricle (Fig. 11). In passing from their ventral 
areas of distribution to their dorsal openings into the venous sinus 
both these vessels lie to the right of the connection between auricle 
and ventricle, i. e., in what corresponds to the right portion of the 
coronary sulcus. We have, therefore, regarded them as together 
equivalent to the right coronary vein. 
The left coronary vein (Figs. 8 and 11, vn. cor. $.) is a single 
main trunk from the left portion of the ventricle and enters the 
venous sinus by a single opening at a considerable distance to the 
left of the sinu-auricular aperture (op.). 
The right and the left coronary veins are distributed to the 
whole of the ventral face and the outer edges of the dorsal face 
of the ventricle. The central portion of the dorsal face is cov¬ 
ered with a system of veins (Fig. 8, vn. crd. m.) which enter for 
the most part into a transverse trunk extending parallel to the 
posterior edge of the venous sinus. From this trunk small vessels 
pass across to the venous sinus into whose cavity they open. This 
system of vessels corresponds very closely to the cardiac veins of 
mammals. 
The openings of what are presumably the right and the left coro¬ 
nary veins in a skate were described and figured by Monro (1785, 
p. 18, Tab. 3, 37). The same was shown in Raja rubus by Tiede- 
