30 Cincinnati Society of Natural History. 
receiving branches, and passing under the first branchial 
arch, but over the second. About 2-3 cm. behind the second 
arch it is joined by the superficial cardinal to form the common 
anterior cardinal vein. 
The common anterior cardinal (or jugular) veins, right and 
left (Figs. XVII, XIX, acr, acl), pass backward and beside 
the pharynx, just external to the corresponding carotid 
artery, and internal to the vagus nerve. They receive four 
sets of branches: (1) somatic veins from the body wall; (2) 
pharyngeal branches, (ph), numerous small twigs from the 
wall of the pharynx; (3) ‘‘club-muscle” branches, from the 
“club-muscle;”’ (4) ““pleural’’ branches from the connective 
tissue in the pharyngeal region. Anteriorly, the courses of 
the right and left anterior common cardinals are similar. Be- 
hind the “club-muscle,’’ however, they are quite different. 
The left anterior cardinal continues in the same general 
direction backward beside the vagus, and above the gills. 
It receives the usual somatic branches, and also a few 
“pleural” twigs from the connective tissue surrounding the 
gill pouches. It also occasionally receives twigs from the 
walls of the gill passages and oesophago-cutaneous duct. 
Posteriorly (Fig. XI, acl), it forms a slight projection from the 
roof into the left pericardial cavity, as before described. It 
passes between the left pronephros, from which it receives a 
twig, and the alimentary canal, and empties into the antero- 
lateral angle of the dilated posterior portion of the sinus 
venosus. 
The right anterior cardinal, on the other hand, toward the 
posterior end of the “‘club-muscle,” leaves the pharyngeal 
wall, passes downward toward the posterior end of the “‘club- 
muscle,” and crossing over toward the median line, empties 
into the ¢xferior jugular vein. (Fig. XIX, jv) The remain- 
ing area corresponding to that supplied by the left anterior 
cardinal on the other side of the body is supplied by the 
portal system. 
The inferior jugular vein (Figs. X, XVII, XVIII, jv) 
arises from the posterior end of the ‘‘club-muscle,” from 
which it emerges on the ventral surface. It passes backward 
a little to the left of the median line, immediately over the 
ventral body wall. After receiving the right anterior cardinal 
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