REPORT ON THE TUNICATA. ' 
171 
otherwise simple alimentary canal. The intestine is thin walled and of great length. It 
stretches for a considerable distance beyond the stomach posteriorly, and then turns round 
to run forwards parallel to its first part and to the stomach. The intestinal loop is thus 
very long and narrow. The rectum does not extend very far forvrards. 
The post-abdomen contains both mature ova and spermatic vesicles, so that both 
reproductive elements seem to be formed in the Ascidiozooid at the same time in this 
species. The reproductive organs are not confined to the post-abdomen, but cover also a 
part of the long intestinal loop. The distance to which the post-abdomen may extend is 
very variable. The numerous spermatic vesicles are ovate or elliptical in form, and are 
united in groups by delicate ducts which join to form the vas deferens. This is a wide 
and rather conspicuous opaque tube which is coiled spirally and may be traced forwards 
alongside the intestine and rectum to the peribranchial cavity. In its entire extent its 
course is greatly convoluted. The mature ova are large and of an opaque yellow 
colour. Embryos and tailed larvse are found in the peribranchial cavity, mainly on the 
dorsal edge, but there is no incubatory pouch. The tailed larvae are large (PI. XXIII. 
fig. 13), and have three very conspicuous adhering organs placed anteriorly. There is 
only one pigmented sense-organ, and it is placed near the posterior end of the body. 
Atopogaster informis, n. sp. (PI. XXIV. figs. 11-15). 
The Colony must have been of large size, and probably was more or less rounded in 
form and not pedunculated. The colom* is light grey, and the surface is rather uneven. 
The Ascidiozooids are large, and have rather a long and narrow shape ; they are 
about 1‘2 cm. antero-posteriorly and 1 mm. in greatest breadth. The body is not 
distinctly divided into regions. 
The Test is firm and cartilaginous. It is of a pale grey colour, and is fairly trans- 
parent. The homogeneous matrix is crowded with small rounded test cells, and no 
bladder cells are present. 
The Mantle is moderately strong, and the musculature is well developed on the 
thoracic part of the body. The muscle bands are nearly all longitudinal, and they run with 
great regularity. There is little or no musculature on the abdomen and post-abdomen. 
The Branchial Sac is fairly large, and the stigmata are numerous. The transverse 
vessels are wide and have no horizontal membranes. The stigmata are of moderate 
length and are regularly placed.. 
The Dorsal Lamina is represented by a series of short stout languets. 
The Tentacles are large and numerous ; they are all of much the same size. 
Locality. — Unknown. 
This species is based upon a fragment of a colony which was found in a bottle 
containing a number of pieces of Compound Ascidians preserved in absolute alcohol. 
