1915. | A. OKA : The Tunicata of the Indian Museum. 25 
intermediate ones. The meshes are much longer antero-posteriorly than transversely 
and contain each three long narrow stigmata. 
The Dorsal Tubercle is cordate in shape, and is placed antero-posteriorly, with 
the opening at the anterior end, slightly to the left of the median line. The horns 
are both turned inwards (Pl. IV, fig. 9). 
The Dorsal Lamina is a simple membrane with no ribs and no teeth. It is 
rather broad. 
The Alimentary Canal forms a double loop on the left side of the branchial sac 
(Pl. IV, fig. 8). It consists of a very short oesophagus and a large intestine bent in 
the form of the letter S, of which the first loop is almost closed. There is no distinct 
stomach. The anus is bilabiate. ; 
The Gonads are inconspicuous. No compact ovaries are present, but a large 
number of eggs, some very small and some larger, are found imbedded in the mantle 
on its inner surface over the intestinal loop. The largest eggs measure about 
0°3 mm. in diameter. 
Locality.—Laccadive Sea, at Station 245, 12° 40’ 28” N., 74° 2’ 45” E.; depth 
449-465 fathoms, bottom green mud; October 14th, 1808. 
This species belongs to that group of Ascidia which is characterized by the 
presence of asperities on the outer surface of the test, but differs from all of them 
hitherto known in one or other of the distinctive characters, either in the number of 
tentacles, or the condition of the dorsal lamina, or the number and arrangement 
of the internal longitudinal bars in the branchial sac. At first I took it to be A. don- 
nant, Herdman, recorded from the Gulf of Manaar, Ceylon; but the latter has fifty 
to sixty tentacles, a strongly ribbed dorsal lamina, and about half a dozen stigmata 
in each mesh of the branchial sac, and can by no means be identified with our 
species in spite of their resemblance in the external form. 
Ascidia hyalina, n. sp. 
(Ei aes pl Os fes. 11 and 12>. pl. V, fig. 1.) 
External Appearance.—The body is irregularly ovate in outline, and is much 
flattened laterally (Pl. IV, fig. 11). The apertures are both sessile, inconspicuous ; 
they are both in the anterior part of the body and are not far distant from each 
_ other. The surface is naked and smooth. The colour is a pale transparent grey. 
The animal appears to have been attached by the left side to branches of a bryozoan 
colony. The size of the body is 20 mm. in length and 14 mm. in breadth. 
The Test is thin, soft, and gelatinous; it is almost colourless and quite trans- 
parent. 
The Mantle is delicate and transparent, with the musculature very feebly deve- 
loped. In some places, especially near the atrial aperture, blood vessels with minute 
branches are very distinctly visible. 
The Tentacles are simple, filiform, and not numerous. 
The Branchial Sac is rather delicate. The transverse vessels are of three differ- 
ent sizes, three of the smallest ones occurring between those of the larger sizes 
