VAN NAME: COMPOUND ASCIDIANS. 409 
five slight lobes besides tiie long simple languet. The ganglion is 
elliptical and the rounded dorsal tubercle is situated close to it. 
The oral tentacles appear to number about 12, of two sizes placed 
alternately. The endostyle is probably nearly straight when the 
branchial sac is fully expanded, but in preserved specimens it is almost 
always more or less sinuous. There are usually 10 or 11 rows of 
stigmata, though in some colonies ©nly 9, with from 16 to IS in a row 
on each side. The three or four stigmata nearest the endostyle are 
successively smaller as that organ is a]>proached. The transverse 
vessels, are strongly muscular, but the median dorsal vessel is slender 
and inconspicuous. It does not bear the dorsal languets, these being 
placed on the transverse vessels of the left side about opposite the 
fourth or fifth stigma from the dorsal end of the row. The languets 
are directed posteriorly. There are none on the transverse vessels of 
the right side. 
The wall of the stomach is thick and has usually about 30 or 40 
(in a few colonies only 15 to 20) sharply defined narrow longitudinal 
ridges, which in some individuals are very regular and extend the 
whole length of the stomach. In other individuals, some of the ridges 
branch and anastomose, or terminate before the end of the stomach is 
reached. Sometimes the branching occurs to such an extent as to 
form a network of ridges over a part of the stomach wall. The writer 
has not observed this over the whole surface of the stomach; in all 
cases, on some parts of it the regular longitudinal arrangement of the 
ridges is preserA-ed. The intestinal loop, as usual in this group, is 
commonly twisted through a half turn, bringing the stomach to the 
dorsal side. Often, however, the twisting amounts to only a quarter 
turn, or even less. 
The ovaries are situated in the anterior part of the post-abdomen; 
the testes, however, extend through the greater part of the length of the 
post-abdomen. The epicardium is often visible as a tube of large 
diameter, which extends along in the right side of the abdomen and 
post-abdomen nearly to the posterior end of the latter. The sperm 
duct, a very tortuous thick-walled tube of varying diameter, extends 
alcjng in the left side of the post-abdomen and abdomen, and running 
beside the rectum, ends near the anus, and the heart, as usual in this 
family, is situated at the extreme posterior end of the post-abdomen. 
The eggs develop into tailed larvae in the atrial cavity of the parent. 
Sometimes as many as a dozen embryos and larvae of different sizes and 
stages may be seen in the atrial and peribranchial cavity of a zooid. 
