PARKER AND DAYIS : HEART BLOOD VESSELS IN FISHES. 167 
ventral vessel is formed from the fourth and fifth commissural 
arteries instead of from the fourth only, and the dorsal vessel is not 
definitely shown to be present. In Scyllium, however, according 
to Hyrtl (’72, p. 267) a dorsal vessel is present; but it arises 
from the fourth commissural arteries which also give rise to paired 
ventral vessels. In Acanthias and Squatina Hyrtl (’72, p. 269) 
describes only ventral vessels; these are, however, paired and 
only the right one extends to the ventricle. 
In Carcharias the epigastric artery is distributed to the muscles 
which surround the pericardial space. According to Hyrtl (’72, 
p. 269 and 271) this artery also occurs in Acanthias and Zygaena. 
It has been identified in Squatina (Hyrtl, ’72, p. 269) and in Mus- 
telus (Parker, ’87, p. 697), in both of which it anastomoses with 
what we have called the coracoid artery, thus establishing connec¬ 
tions between the subclavian and the median hypobranchial systems. 
The ventral coronary artery (PI. 1, fig. 1, cor. v.) in Carcharias 
divides into three vessels, a median, a right, and a left, and is thus 
distributed over the ventral surface of the ventricle. The dorsal 
coronary (PI. 2 , fig. 4, cor. cl.) also divides into three branches, 
one of which goes to the right side of the ventricle and to the 
auricle, another to the left side of the ventricle, and a third by 
passing around the conus to the left anastomoses with branches of 
the ventral coronary. 
The coronary arteries in sharks have not heretofore been described 
in detail except in the case of Selache, in which, according to the 
careful account given by Pavesi (’74, p. 67, 68), the plan of distri¬ 
bution coincides almost exactly with that found in Carcharias. 
As in the cases of other sharks, Carcharias possesses no posterior 
coronary arteries. 
In Raja erinacea the lateral hypobranchial arteries (PI. 1, fig. 2, 
h’brn. 1.) show great diversity, extending in some instances over 
the branchial region from the second to the sixth arch, while in 
others they are restricted to the middle portion of this region. 
Any efferent branchial artery of any arch between the second and 
sixth may, or may not, connect with the lateral hypobranchial; 
connection is, however, the rule with vessels near the middle of the 
series and the exception with those near the anterior and posterior 
extremes. So far as these connections were concerned, none of the 
specimens examined by us were bilaterally symmetrical. 
