REPORT OX THE TUXICATA. 
167 
abdomen the lono[itudinal bands become more numerous and form a strono- muscular 
investment to the reproductive organs. The branchial siphon is rather lono- (PI, 
XXIII. figs. 3, 5), and its anterior end is distinctly six-lobed. In some cases the lobes 
are large and widely separated (PI. XXIII. fig. 5). The sphincter is well developed. 
The branchial sac is rather long and narrow, and contains many rows of stigmata. 
The most noteworthy featime in regard to it is the comparatively great width of the 
transverse vessels, which are all of the same size, and have bands of muscle fibres running 
along their length (PI. XXIII. fig. 4, m.f.). In some specimens neither the transverse 
vessels nor the stigmata are quite so wide as the figure shows. The ciliated cells placed 
along the sides of the stigmata are large and distinct, and have their free ends 
pointed. 
The endostyle is narrow and inconspicuous, its course is undulating. The languets 
are not numerous, but they are rather large ; they are tentacular in form and are pointed. 
The tentacles are rather inconsj)icuous, and the aperture of the dorsal tubercle is very 
small. The nerve -ganglion is large and globular. 
The alimentary canal forms a long narrow loop (PI. XXIII. fig. 3). The oesophagus 
commences at the posterior end of the dorsal edge of the branchial sac, and runs directly 
backwards. It is funnel-shaped at its upper end (PI. XXIII. fig. 3, ce.), and then rapidly 
narrows to form a slender tube which opens into the anterior extremity of the some- 
what ovate stomach. The long axis of the stomach is directed antero-posteriorly, and 
the anterior end is the wider and more rounded of the two. The wall of the stomach 
is usually somewhat folded transversely. The intestine emerges from the narrow posterior 
end of the stomach, and runs backwards as a tube of variable calibre and irregular course 
(PI. XXIII. fig. 3, {.). It then turns round vmntrally and anteriorly, and becoming 
suddenly wdder runs forwards as the rectum parallel to the intestine, stomach, and 
oesophagus to reach the posterior end of the brancliial sac, where it crosses over to the 
dorsal side, and finally opens into the peribranchial cavity. 
The reproductive organs lie completely behind the intestinal loop. Both ova and 
spermatic vesicles may be found in the same Ascidiozooid. The vas deferens is a long 
tube, but it is not so conspicuous as is usual in the Compound Ascidians. Tailed larvae 
were found in some Ascidiozooids lying in considerable numbers in the peribranchial 
cavities. They have long narrow l)odies (PL XXIII. fig. G) provided anteriorly with 
three slender adhering papillae, and the pigmented sense-organs (of which two are 
present) are placed close together near the posterior end of the body. 
In several of the Ascidiozooids ova of smaller size than those in the post-abdomen 
and small embryos in various stages of development were found in the dorsal part of the 
peribranchial cavity. A careful examination showed that these were Crustacean embryos, 
and a few completely developed Nauplii were found amongst them. They evidently 
belong to the Copepoda living in the common cloacal cavities of the colony, and as the 
