1915.] A. OKA : The Tunicata of the Indian Museum. 17 
The tentacles are much branched, there are six to eight large and six to eight 
smaller placed alternately, with some very small intermediate ones. The dorsal 
tubercle is small, cordate in outline, with the opening anterior and both horns 
turned in. The dorsal lamina is a plain membrane. 
The branchial sac has six folds on each side, but there are on each fold about 
twelve internal longitudinal bars instead of five, and only one in the interspace 
instead of three. In this respect the specimens are sharply distinguished from the 
type of the species, but otherwise they agree quite well, so that it seems inadvisable 
to separate them specifically on the strength of this single character. Possibly the 
species may have a very wide range of individual or local variation in the arrange- 
ment of the internal longitudinal bars. The arrangement of the transverse vessels 
is also somewhat different; in the type specimens there are seven narrower trans- 
verse vessels between each pair of very much wider, while in our specimens they are 
of three different sizes placed alternately after the scheme I, 3, 2, 3, I... The 
meshes in the interspace between the folds are elongated and contain about nine 
stigmata each. Most of the meshes are crossed by a narrow horizontal membrane. 
As Herdman has already pointed out, this species is very cosely allied to 
Microcosmus gleba, Traustedt, from the Pacific. The differences are, in fact, rather 
slight, being confined to some details of the branchial sac, and it seems doubtful 
whether the two forms should be regarded as specifically distinct or not. I have 
preferred, however, to leave the question to those investigators who have the oppor- 
tunity of comparing the original specimens of both forms. It is, by the way, also 
questionable if the Island of Banca where Microcosmus gleba was found should be 
included in ‘‘ Stille Hav’’, as given in Traustedt’s paper and quoted by Herdman. 
Fam. STYELIDAE. 
This family is represented in the collection by three species of Polycarpa, one 
of which is new to science, and a minute solitary form for which it was found 
necessary to form a new genus. The latter is especially interesting, as it exhibits a 
combination of characters which is intermediate between the Styelidae from among 
the simple Ascidians on one hand and the Polystyelidae from among the compound 
Ascidians on the other. 
Polycarpa cryptocarpa, Sluiter. 
(PE fist 13.) 
Polycarpa cryptocarpa, Sluiter, Über einige einfache Ascidien von der Insel Billiton. Natuurk. 
Tijdschr. Ned. Ind. D. XLV, 1885. 
Localities.—(I) Madras coast, 20 fathoms. Five specimens. (2) Off C Negrais, 
Burma, at Station 384; 16° 0’ N., 93° 37’ E.; depth 40 fathoms; bottom coral; 
February 22nd, 1909. One specimen. 
The specimens agree quite well with the original description by Sluiter except 
in certain details of internal structure. The tentacles are not all of one size as in 
the type specimens, but are of three different sizes placed alternately after the 
