EEPORT ON THE TUNICATA. 
105 
The branchial sac is thin-walled and readily torn. The stigmata are large with 
narrow ends (PL XIY. figs. 8, 11, sg.). There are at least four rows on each side of 
the sac. 
The endostyle is fairly straight. It is conspicuous. The languets are very short, 
and they are not united by a membrane in the middle dorsal line (see PI. XIV. fig. 11, 1); 
the stigmata pass in a continuous series from the one side of the branchial sac to the 
other across the dorsal edge. 
The tentacles are remarkably short. They are merely small triangular stumps and 
seem to be in cpiite a rudimentary condition. They form a marked contrast with the 
well-developed tentacles of other members of the genus, such as Colella pedunculata. 
The nerve ganglion and neural gland form an ellipsoidal mass, with an anterior pro- 
longation, the neural duct, which opens just inside the prebranchial zone by a simple 
aperture, the dorsal tubercle. 
The alimentary canal is large and conspicuous. In the young Ascidiozooids, of which 
there are a great many in the colony, it is much elongated autero-posteriorly (see PI. XIV. 
fig. 12). The oesophagus in the figure is rather larger than in most of the other 
specimens examined, but it is always of considerable length. The stomach is oval in 
shape, and along with the oesophagus runs directly backwards, forming the dorsal part of 
the visceral mass. After the stomach comes a short and very narrow piece of intestine 
which usually has a small posteriorly directed csecal process (PI. XIV. figs. 12, 13). 
This forms the termination of the visceral mass. Figure 13 shows the shape of 
this region of the canal in another specimen. The intestine then enlarges (PI. XIV. 
fig. 13, i.), and turning anteriorly runs forward to cross the oesophagus, and thus enters 
the dorsal part of the peribranchial cavity. The ventral part of the visceral mass is 
formed by the long intestine. In the older Ascidiozooids the alimentary canal is not so 
much elongated as in the younger ones, the stomach is more globular, and the intestine 
is relatively shorter and wider. The vascular appendage arises rather on the ventral 
edge of the posterior end of the abdomen (PI. XIV. fig. 12, v.ap.). 
In the intestinal loop, and just alongside the stomach, a number of small ova, forming 
a compact mass, are always found in the young Ascidiozooids (PI. XIV. fig. 12). In 
older ones one or two large mature ova are generally still present, but in addition there 
are always some ovate opaque seminal vesicles and a vas deferens. In most of the 
mature Ascidiozooids the dorsal part of the peribranchial cavity is prolonged into an 
incubatory pouch of considerable size (PI. XIV. fig. 10). It is usually sac-shaped, with 
a very narrow mouth, and was never observed to be spirally coiled. These incubatory 
pouches are filled with embryos in various stages of development, and a large number 
of tailed larvae are also present. In the larvae (PI. XIV. fig. 14) the body is narrow 
and elongated, and the tail is very long, being in some cases capable of being wound nearly 
twice around the body. A Amry broad delicate membrane fringes the tad upon each 
(ZOOL. CHALL. EXP. PART XXXVIII. 1885.) Pp 1 4 
