538 Wisconsin Academy of Sciences, Arts, and Letters. 
vein. On the left surface of the esophagus the veins of this series 
are broken up into small tracts which reassemble and form trunks 
from the left dorsal parietes. Only one large vein leads directly 
from the left dorsal parietes to the left jugular vein, (Fig. 1-x). 
It is quite uniform and runs along the body wall, as does the 
right anterior azygous vein (Fig. 2), but carries blood forward 
and empties into the left jugular at the angle of the jaw. This 
vein does not seem to have been mentioned before and does not 
exist in Zamenis constrictor (Atwood, T6). 
There is a tendency for the parietal veins to form a small 
azygous trunk (Fig. 1, AV) posterior to the termination of the 
vein mentioned above, but such a condition is not uniform. This 
suggests the remains of the left anterior azygous vein. 
In the region of the heart three, or less, veins leave the left, 
dorsal parietes and join the reticulation of veins on the left sur¬ 
face of the esophagus then assemble to form the first trunk 
which enters the left jugular vein (Fig. 1). These parietal 
veins are variable and are the remains of the left posterior azy- 
geous vein. Zamenis differs from ThamnopJiis in that the veins 
from the left and right parietes do not form a finely divided 
reticulum on the esophagus but enter the jugular veins more 
directly (Atwood, T6). 
On the ventral surface of the trachea, between the two jugu¬ 
lar veins a longitudinal trunk occurs (Fig. 1). It receives blood 
from the trachea and is connected with the jugular veins and 
the fat body. The blood leaving the trachea has probably been 
more or less aerated in its walls. 
The connections between the left jugular vein and the epi¬ 
gastric are described along with the epigastric vein. 
The left jugular vein receives blood from the following 
sources: head, esophagus, left dorsal parietes, trachea, fat body, 
left thymus gland, thyroid gland and epigastric vein. 
The Afferent Renal Veins. 
The caudal vein runs parallel to, and in close contact with, 
the caudal artery—both lying in the haemal canal of the tail. 
Above the anus the caudal vein divides to form two trunks, the 
right and left afferent renal veins; (illiac veins. Cope, ’00; 
venae renalis advehens, Schlemm, ’27; renal portal veins, 
O’Donoghue, ’12). From a position dorsal to the anus these 
