780 PROFESSOR W. C. M‘SINTOSH AND MR E. E. PRINCE ON 
mandible.* Both arteries meet in front of the symphysis, and return by a single median 
vein along the floor of the mouth. The later developments of the hamal system at a 
stage—in, say, Gadus morrhua—when the caudal artery extends along fully two-thirds 
the length of the tail, are as follow :—Four branchial arteries can be made out, and 
a submaxillary artery passes beneath the eyes, while a return-current is directed over 
the eyes, along the supraocular vein. The coeliac artery, before described as leaving 
the aorta in the pectoral region, passes over the liver, along the ventral surface of the 
intestine, and sends an arterial branch upward, which, bifureating, supplies the walls of 
the intestine,—the main trunk continuing its ventral course, and ascending in front of the 
urinary vesicle,—over the walls of which it passes to the vena vertebralis. The venous 
trunks form a more complex system—the simple subintestinal loop which breaks up into 
an elaborate hepatie capillary network still continues, but it is joined by a large visceral 
trunk on the posterior side of the liver. This latter vessel leaves the caudal vein at the 
root of the tail, passes ventrally in front of the urinary vesicle and over the walls of the 
rectal portion of the intestine to the termination of the mid gut. At this point a 
large venous trunk branches off dorsally to join the posterior cardinals. Minor venous 
branches run from the walls of the stomach and pyloric portion of the intestine, forming 
the first indication of the portal system—all their blood finally passing in front of the 
liver into the sinus venosus by the hepatic veins. The liver, the dorsal lobe of which 
lies above the alimentary canal and behind the swim-bladder, is seen chiefly as a rounded 
mass (the left and ventral lobe) projecting boldly into the surface of the yolk below, and 
lying immediately in contact with the posterior pericardial wall. The proximity of the 
liver with its rich vascular plexus, and of the large ductus Cuvieri pouring a stream into 
the capacious sinus, suggest the possibility that it is at this point that the assimilation 
of yolk-matter is most active. It is absorbed and conveyed to the heart by the venous 
blood. The continuity of the wall, limiting the pericardial chamber (pd, Pl. VII. fig. 9), 
appears to be unbroken, and roofs over a sub-pericardial space (ss) filled with a serous plasma 
and disintegrated yolk. A suboral chamber in many cases seems also to be shut off by 
this membrane (Pl. VIII. figs. 6, 7). The heart’s pulsations partake of a progressive 
vermiform movement, the auricle, continuous with the sinus venosus, contracting first, 
and the successive parts (of the auricle) contract in order, the ventricle dilating as the last 
part of the auricle closes. As the ventricle contracts, the open end of the auricle dilates. 

- The progressive systole being triple, : tee ol 2 3 
B : ; a C)\ contract 
= (See accompanying diagram,) : s , (4)—(B)—(f) dilates 
L The diastole also is threefold, and D contracts ) (A)—(B)—(C) dilate 
simultaneously with the dilatation of A, . ) (D) contracts. 
The delicate pelagic forms chiefly considered in these pages present a great contrast to 
* Gorre is certainly incorrect, as Batrour pointed out (No. 11, p. 645), in denying that a mandibular artery is 
ever developed in Teleostei (No. 59). 
