go ALLEN 
of the second and third dorsal nutrient branchial veins. The 
combined vessel thus formed passes dorsad behind the second 
levator arc. branch. internus muscle, and after receiving a 
branch from it and another from the second obliquus dorsalis 
muscle, terminates in the jugular. In this specimen the third 
and last dorsal branchial muscle vein arose from 2 branches. 
The most cephalic one is a dorsal nutrient branchial vein from 
the last branchial arch, and the other has its source from the 
pharyngo-clavicularis externus, pharynx, and the occipito- 
clavicularis muscle. The dorsal branchial vessel thus formed 
passes in a dorso-cephalic direction above the corresponding 
artery. After crossing the last efferent branchial artery it 
receives a good-sized branch coming from the last 2 internal 
branchial levator muscles, and then empties into the jugular 
directly behind the second dorsal branchial vein, but before 
emptying into the jugular it receives the 7hymus ven from the 
rear. This vein (fig. 1; not lettered) runs cephalad along the 
ventral margin of the gland, receives several branches from it, 
and shortly before reaching the anterior end of the thymus, 
curves ventrad; crossing over the posterior encephalic and 
jugular veins, finally terminates in the third dorsal branchial 
muscle vein shortly before the latter empties into the jugular. 
In another specimen from the one figured, the dorsal nutrient 
vein from the second branchial arch joined the first dorsal bran- 
chial muscle vein immediately after it had pierced the first 
levator arc. branch. internus muscle. The second dorsal 
branchial muscle vein took its origin from the third dorsal 
nutrient branchial vein and received branches from the third 
obliquus dorsalis muscle and the second levator arc. branch. 
internus muscle; while the third and last dorsal branchial 
muscle vein had its source from the fourth nutrient branchial 
vein and a branch coming from the fourth obliquus dorsalis 
muscle. The thymus vein emptied into the posterior encephalic 
vein, and the vein from the pharyngo-clavicularis externus, 
pharynx, and the occipito-clavicularis muscle, which is usually 
the source of the last dorsal branchial muscle vein, crossed the 
jugular and posterior encephalic veins and terminated in the 
thymus vein. 
