VAN NAME: SIMPLE ASCIDIANS. 539 
2, 4, etc. They number all told about sixty. In the intervals 
between them are slender vessels of a fifth order crossing without 
interrupting the stigmata but these are often wanting or intermittent, 
extending only over a few stigmata before they terminate. About 
midway on the interspaces between the first and second folds there 
are on each side of the sac two internal longitudinal vessels close 
together. Except for these, the internal longitudinal vessels are all 
borne on the folds or so near the bases of the latter (either dorsal or 
ventral to a fold) that they clearly belong to a group borne on one of 
the folds. They are distributed as follows in the largest specimen: 
vidv. (19) 2 (18) (14) (13) (11) en. 
The stigmata are longitudinal in direction and are separated by very 
narrow vessels. They are very numerous, thirty or forty or more 
on the interspaces between folds (counting from the actual beginning 
of the plications, not from the outlying internal longitudinal vessels 
above mentioned). They are about equally as numerous dorsal to 
the first fold, and ventral to the last fold as on the interspaces between 
folds. On the folds the stigmata are narrower than on the interspaces 
and also very numerous, but difficult to count because of the closely 
placed internal longitudinal vessels. The above numbers of stigmata 
apply to the anterior and middle parts of the sac. Posteriorly they 
are fewer and less regular as the folds come nearer together. 
Stomach elongated, with thick glandular walls. It is not conspicu- 
ously distinguished externally from the intestine into which it gradu- 
ally tapers off. Intestinal loop widely open for a short distance; 
the intestine then approaches the stomach along which it lies, some- 
what overlapping it. 
Gonads elongated, hermaphroditic. One on each side of the body. 
That on the left partly in the open space of the intestinal loop, cross- 
ing the dorsal branch of the loop at right angles. The ovary, consist- 
ing of a rather large oviduct with masses of small eggs along its sides, 
occupies the axial part of each gonad. The main sperm duct accom- 
panies the oviduct giving off lateral branches to large masses of small 
pyriform or lobed testes which surround and almost conceal the eggs 
from view and spread out over the mantle considerably beyond the 
borders of the ovary. The oviduct extends but a short distance 
beyond the end of the gonad, terminating with a large irregularly lobed 
