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 1st 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 XXVI. 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, yvs), where their course has already been described. The 

 cranial circulation is not readily made out. A large curved trunk, fig. 2.— Anterior curve of the portal 

 the hyoidean (PL XXI. fig. 4, cv), leaves the anterior branchial 



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 



