722 
PROFESSOR T. J. PARKER OR THE 
holobranch in communication {com. 2), and others uniting the whole series of efferent 
branchial arteries with the subclavia.ns (Plate 34, fig. 2 ; and Plate 35, fig. 6, com. 1). 
But it is in the venous system that we find the most striking cases of anastomosis. 
The hyoidean sinuses communicate with the jugulars, with the inferior jugulars, and 
with one another (Plate 34, fig. 2) ; the cardinals are placed in communication with 
one another (Plate 35, fig. 10) and with the portal vein (figs. 10 and 12); the lateral 
veins unite with one another (fig. 1), as also do the cloacal veins (Plate 3G, fig. 14); 
the anterior ventral cutaneous vein opens in front into the lateral, behind into the 
iliac veins (fig. 14) ; the lateral cutaneous is connected with the subscapular vein in 
front and with the caudal and dorsal cutaneous veins behind. 
The diagram, fig. B (woodcut), is intended to bring out these peculiarities of the 
venous system. There can be little doubt that, in many instances, alternative courses 
are open to the returning blood, so that the venous portion of the circulation is by no 
means so definite as in the higher animals. 
Another point of interest is the tendency of the veins to enlarge into great irregular 
sinuses. The cardinals dilate anteriorly into capacious cardinal sinuses, and the hepatic 
veins into an immense hepatic sinus; the blood from the head is poured partly into 
the orbital, partly into the hyoidean sinuses. In fact the majority of the venous 
channels, as will be seen by an inspection of figs. 1 and 2, are of a calibre quite dispro¬ 
portionate to that of the corresponding arteries. 
Thus the veins of a Selachian have more or less of a lacunar character, reminding 
one of what is found in many of the higher Invertebrata. It is a question how far 
this state of things is primary or ancestral, and how far secondary. 
Other matters of general interest are discussed in earlier portions of the paper. 
The most important of these are : the relation of the arteries of the adult to the 
embryonic aortic arches (pp. 689-691) ; the renal portal system (pp. 704 and 714 ); the 
derivatives of the embryonic sub-intestinal vein (p. 709) ; the homology of the lateral 
vein with the epigastric vein of Amphibia (p. 717); and the relation of the blood¬ 
vessels of Selachians to the primary vascular trunks of the Chordata (p. 718). 
Methods of Investigation. 
The arteries may be conveniently injected from the ventral gastric artery, the 
cannula being directed towards the dorsal aorta ; if the operation is conducted 
successfully the whole arterial system is filled, with the exception, of course, of 
the branches of the ventral gastric artery itself. Fine (dental) plaster of Paris 
coloured with vermilion or carmine forms an excellent injecting material. 
The injection of the veins is more difficult. By injecting from the anterior 
lieno-gastric or from the dorsal intestinal vein, the cannula being directed towards 
the main portal vein, the whole of the portal system is filled, the injection usually 
also passing through the spermatico-portal anastomosis into the cardinals, sinus 
