DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 881 
The contraction of the auricle sends the blood into the ventricle, and the latter by 
the bulbus drives it into the four branchial arteries, which terminate in the dorsal aorta. 
The latter passes backward almost, though not quite, to the tip of the tail. Before reach- 
ing its termination (Pl. XX. fig. 1) a twig leaves the artery and goes into the lower lobe of 
the tail, forming, with the returning veins, an arrangement of at least four loops. More- 
over, the caudal vein bends downward, producing a loop or diverticulum just where the 
arterial twig leaves the aorta, and receives the branches returning from the region. The 
four loops referred to form a fan-shaped arrangement, one loop being in front, two median, 
and one posterior. In its course along the under surface of the notochord, the aorta sends 
a twig (Owen’s intercostal) upward at each myotome, and it alternates and inosculates 
with the veins returning to the posterior cardinal. A specimen showing these features 
was found so late as Ist March, and had not long emerged, so that a margin for variation 
must be made. The artery on passing over the urinary vesicle transmits on the left 
side a large trunk to the rectum (a, Pl. XXVI. fig. 2), which by and by divides, a large 
branch sending twigs posteriorly, while the main vessel proceeds along the superior edge, 
giving off branches from its ventral margin. These pass downward and join the great 
portal vein (Pl. XXVI. figs. 1, 2, pv), which slants upward on the right side of the gut to 
proceed to the liver. The forward current in the arterial trunk (Pl. XXVL. fig. 2) goes 
a little distance beyond the point marked b to the point indicated by x, where it is met 
by an opposing current from the artery d. This last current shows a distinct pulsatory 
movement (as in vigorous arteries). Thus, at the point of contact, there is a neutral zone 
which occasionally is thrown a little backward so as to impinge by jerks on the forward 
current. Any difficulty arising from the presence of two diverse currents in the con- 
tinuous vessel is obviated by the ready exit along the comparatively large inferior twigs 
proceeding to the intestine. Streams of blood thus pour all over the intestine in a 
downward direction, and are collected by the great subintestinal (portal) vein. The vessels 
from the anterior artery (see Fig. 2) curve downward to the lower border of the gut, and 
as the intestinal vein in this region is above the lower margin 
of the latter, the branches going to it therefore curve upward. 
On reaching the liver the great intestinal (portal) vein breaks 
up into many branches, and from the margin of the organ large 
vessels pass to the posterior region of the yolk-sac (Pl. XXI. 
fig. 1, yus), where their course has already been described. The 

cranial circulation is not readily made out. A large curvedtrunk, Fic. 2.—Anterior curve of the portal 
the hyoidean (Pl. XXI. fig. 4, cv), leaves the anterior branchial et a 
vessel near the fork of the jaw, forms a loop behind, and passes forward between the eyes. 
Its course is hidden by the pigment of the latter. These vessels are proportionally larger 
than in the salmon, and the same may be said of the jugulars, which are in intimate re- 
lation to the otocysts. Such variations are probably associated with the differences in the 
configuration of the parts in the respective species. The ventral branch resulting from 
the union of the hyoidean and two first efferent branchial arteries, and which supplies the 
VOL. XXXV. PART III. (NO. 19). 6 U 
