170 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
median line on the ventral side of the ventral aorta and give rise 
to a median hypobranchial artery ( h'brn . m.). This extends pos¬ 
teriorly, giving off a large epigastric branch ( e’ga .), and then 
divides to give rise to a ring vessel surrounding the aorta and to 
two coronary arteries, one dorsal (PI. 2, fig. 6, cor. cl.) and the 
other ventral (PI. 2, fig. 3, cor. v.). These extend posteriorly over 
the bulb to be distributed eventually to the respective faces of the 
ventricle. Each coronary shows evidence of division into right and 
left branches. 
Judging from the figures and descriptions of various authors, the 
coronary arteries of most teleostomes conform to the plan in Amia. 1 
Probably in all the higher fishes the vessels leading from the gills 
towards the heart are the fourth pair of commissural arteries. 
Stannius (’46, p. 101), however, described these vessels in the stur¬ 
geon as coming from the third branchial arch and hence corre¬ 
sponding to the fifth commissurals; but this is probably a mistake, 
for, according to Hyrtl (’55, p. 11), the vessels in the sturgeon 
come from the fourth visceral arches as in other higher fishes. The 
cod has been described by Jourdain (’67, p. 192) as receiving its 
coronary supply from the third branchial arch, while Parker (’84, 
p. 117) figures it as coming from the fifth. The vessel in the cod, 
however, is so small and the ventral ends of the efferent branchials 
are so crowded that the exact connections are rather matters of 
interpretation than observation. Since the sturgeon and the cod 
seem to be the only recorded excej)tions to the general rule, and 
since these, as exceptions, are of doubtful value, it may well be that 
in all teleostomes the vessels that leave the gills for the heart come 
from the fourth visceral arches and represent fourth commissural 
arteries. 
Both the right and the left fourth commissural arteries are well 
developed in Amia, and the same is presumably true of the stur¬ 
geon (Hyrtl, ’55, p. 11) and of the pike (Muller, ’41, p. 198). In 
Scomber and Pelamis the right artery is said (Hyrtl, ’55, p. 11) 
1 The chief exception to this statement is to he found iu Orthragoriscus mola, as 
described by Milne-Edwards (’58, p. 341). According to this author, O.mola has lateral 
hypobranchial arteries connecting the efferent branchials of the first, second, and third 
branchial arches. It has a ventral median hypobranchial formed from thfe fourth pair 
of commissural arteries and giving rise to a ventral coronary artery. It further has a 
dorsal median hypobranchial formed from the sixth commissural arteries and giving 
rise to a dorsal coronary artery. This description corresponds so well with what is 
found in some elasmobranchs, and is so unlike what is known to occur in other teleo¬ 
stomes that we have been tempted to call its accuracy into question. Unfortunately, 
we have had no material by which to test this question. 
