BLOOD-VASCULAR SYSTEM OF THE LORICATI 47 
Hyoidean Arteries (Pls. I and II, figs. 1 and 12; Hyo.A.). 
— A short distance above the source of the inferior hyo hyoideus 
arteries, 2 large hyoidean arteries are given off to the hyoid 
arch and the adjacent region. After reaching the hyoid arch 
from the inside, a little behind the hypohyals, the main trunk 
runs along the dorsal surface of the cerato- and epi-hyals; 
making a dorsal bend in front of the interhyal it crosses under 
the preopercular, and after passing through a foramen, which 
is formed by the symplectic, hyomandibular, preopercle, and 
quadrate, anastomoses with the /aczalis-mandibularis artery 
(Pl. I, fig. 1; F.Man.A.). In the embryo the hyoidean artery 
probably furnished the entire blood for the pseudobranchia; the 
current of blood in the facial-mandibular artery was dorsad 
toward the carotids. Also in the adult it would be possible for 
the blood from the hyoidean artery to flow dorsad in the facial- 
mandibular artery as well as ventrad, however, since the facial- 
mandibular is a much larger artery than the hyoidean, it is not 
probable that much of the blood from the hyoidean artery runs 
counter to the current of the facial-mandibular artery. It also 
might be possible at times for the blood in the hyoidean artery 
to flow ventrad, that is toward the efferent branchial artery. 
From Miiller’s (50), Stannius’ (74), and Emery’s (24) descrip- 
tions, one would infer that the hyoidean artery in most bony 
fishes supplied the pseudobranchia, but in Ophzodon the blood 
supply for the pseudobranchia, which will be considered later, 
comes from a branch of the external carotid artery. 
The first branch to be given off from the hyoidean artery is the 
lingual artery (P\. Il, fig. 12; Lin.A.). This vessel leaves the 
hyoidean artery close to the efferent branchial artery, shortly be- 
fore the hyoidean artery reaches the hyoid arch, and each lingual 
artery runs cephalad along the ventral surface of the glossohyal. 
Immediately after the hyoidean artery reaches the hyoid arch it 
gives off the genzohyoideus artery (Pls. I and II, figs. 1 and 12; 
Ghs.A.) to the geniohyoideus muscle. One of these arteries is 
much longer than the other ; sometimes it is the right and again it 
is the left. Inthe specimen from which fig. 12 was drawn, the 
right artery was the longer ; it passed entirely around to the outer 
ventral surface of the ceratohyal and then curved cephalad, pass- 
