BLOOD-VASCULAR SYSTEM OF THE LORICATI 49 
larger left pharynx artery (Pl. II, fig. 12; L.Phar.A.) sup- 
plies the pharynx and similar muscles on the left side. Soon 
after the left pharynx artery leaves the main stem it gives 
off the large coronary artery (Pls. I and II, figs 1 and 12; Cor.- 
A.) for the heart. For some little distance this vessel runs 
along the dorsal surface of the ventral aorta and then divides 
into a dorsal and a ventral trunk. The dorsal coronary artery 
(Pl. II, fig. 12; D.Cor.A.) continues along the dorsal surface of 
the ventral aorta and bulbus arteriosus to the heart as the prin- 
cipal vessel. Usually this vessel bifurcates in the region of the 
conus arteriosus, one branch penetrating directly into the mus- 
cular layer of the ventricle, while the other is a superficial vessel, 
distributing itself over the dorsal surface of the ventricle; or 
sometimes both may be superficial vessels. It is probable that 
these vessels also supply the auricle, although I have never 
been able to trace them further than the ventricle. Each of 
these vessels gives off a small artery, which encircles the bul- 
bus and anastomoses on the ventral side with the ventral coro- 
nary artery, and from this circular artery several small vessels 
are given off to the bulbus and the ventricle. The ventral 
coronary artery (Pl. Il, fig. 12; V.Cor.A.), which is much 
smaller than the dorsal vessel, also runs caudad in the outer 
coat of the ventral aorta, but it supplies only the ventral walls 
of the ventral aorta and the bulbus. None of its branches 
reaches the ventricle. In Scorpenichthys the pharynx arteries 
arise as separate arteries from the second pair of efferent 
branchial arteries, and the coronary artery comes from the left 
pharynx artery, close to its point of origin from the efferent 
branchial vessel. 
The Ventral Artery (Pls. I and Il, figs. 1 and 12; Ven.A.) 
is the largest of any of the vessels arising from the ventral 
ends of the efferent branchial arteries. In Ophzodon this ves- 
sel has its origin from the ventral union of the second and third 
pairs of efferent branchial arteries. This does not appear to 
be the common arrangement among other bony fishes; in Hex- 
agrammos, Scorpenichthys, and Sebastodes the ventral artery 
has its source from the second pair of efferent branchial vessels. 
Continuing caudad along the ventral surface of the pericardial 
Proc. Wash. Acad. Sci., June, 1905. 
