286 
THE VOYAGE OF H.M.S. CHALLENGER. 
walled stomach (PI. XXXIX. fig. 18). The intestine leaves the posterior end of the 
stomach and at once turns dorsally and then anteriorly. It lies close to the oesophagus 
at the posterior end of the branchial sac. 
The testis forms a large rounded mass placed alongside the intestine (see PI. XXXIX. 
fig, 18). The vas deferens commences by coiling spirally around the testis. No ova and 
no embryos were discovered in the colony. 
This form is one of those which make me very doubtful as to the propriety of separat- 
ing the genera Didemnum and Leptoclinum by the number of rows of stigmata in the 
branchial sac. If that course were adopted, the present form would have to be regarded 
as a species of Didemnum, but the extreme thinness of the colony (about 1 mm.) is a 
strong argument against such a view. Then, again, it is so similar in some respects to 
the specimens of Leptoclinum tenue from the west coast of South America and, from the 
North Atlantic, that for some time I hesitated to describe Leptoclinum propinquum as a 
distinct species, and cannot therefore bring myself to regard these two forms as belonging 
to separate genera. 
Leptoclinum neglectum, n, sp. (PL XXXVIII. figs. 10-13). 
The Colony is irregularly shaped, and incrusting. It is attached by the greater part 
of its lower surface. The upper surface is fairly smooth. The colour is a dull white. 
The length is about 3 cm., the breadth 1'5 cm., and the thickness 2 mm. 
The Ascidiozooids are numerous but rather small. They , are distributed evenly over 
the surface of the colony, and are not arranged in definite systems, A few slit-like 
common cloacal apertures are visible. 
The Test is moderately hard and firm. It is of a greyish-white colour in most parts, 
and is quite o^Daque. The matrix contains small rounded test cells and large numbers of 
calcareous spicules. No bladder cells are present. The spicules are large and of regular 
stellate form. 
The Mantle is moderately strong, both transverse and longitudinal muscles are present. 
The Branchial Sac is short and wide. The stigmata are large and regularly arranged. 
The ciliated cells are distinct. 
Tice Tentacles are few and of small size. 
The Alimentary Canal forms a long narrow loop. 
Ijocality. — Unknown. 
This colony, which was found in a small bottle without a label, and of which therefore 
the locality is unknown, is in some respects allied to Leptoclinum annectens, and in others 
resembles Ljeptoclinum tenue, but is, I consider, sufficiently distinct from both to be 
entitled to a separate description. 
