1915.] A. OKA: The Tunicata of the Indian Museum. 23 
Hope. So far as the shape and condition of the test is concerned, especially in the 
presence of longitudinal grooves on the outer surface of the siphons, it agrees pretty 
well; but the number of lobes at the branchial and atrial apertures is different, 
being in our specimen seven and five instead of the usual eight and six respectively. 
As there is only one specimen in the collection it is impossible to decide whether 
this is an abnormal condition or a constant specific character. In the latter case it 
should of course be considered as a distinct species and be given a new specific 
name. 
The body is ovate in shape, with anterior end narrower and pointed and the 
posterior broader and rounded ; it is somewhat compressed laterally, and is attached 
by the whole of the left side. The apertures are borne on large prominent siphons, 
the sides of which are channelled by well marked straight grooves running down 
longitudinally from between the lobes. The branchial siphon is anterior, terminal, 
and is directed anteriorly ; it is not curved and the aperture has seven lobes. The 
atrial is situated about one-third the way down the dorsal edge, it is nearly as large 
as the branchial, and is directed anteriorly and somewhat dorsally ; the aperture 
is only five-lobed. The surface is a little roughish, otherwise it is smooth and 
regular, and is quite naked. The colour is a light yellowish-grey. The test is 
cartilaginous and semi-transparent; it is not thick, the thickness varying from 
0°5 mm. on the left side to nearly I mm. on the siphons. Size of the body: 43 mm. 
long and 22 mm. broad. 
Sluiter (11) described two specimens of this species from the island Billiton; 
strangely enough they had both only seven longitudinal grooves on the branchial 
siphon, the same as our specimen, and not eight as in the type described by Heller. 
The atrial siphon, however, seems to have had the usual number of lobes and 
grooves, as Sluiter makes no mention of abnormalities about them. 
What makes me more inclined to believe that the test described above belongs 
to this species, is the presence in another bottle, also containing Ascidians from the 
Andamans, of a specimen of Ascidia, devoid of test, which agrees tolerably well with 
the description given by Sluiter. It is rather small, being only 25 mm. long and 
7 mm. broad at the widest part, so that it is of course questionable whether it 
belonged to the same individual as the test. I insert here a brief account of this 
specimen in order to show how far it agrees with the internal body of A. canaliculata 
as described by Sluiter. As Heller gave no detailed account of the internal organs 
it is impossible to compare our specimen with the original type of the species. 
The mantle is thin and delicate on the left side; on the right it has well 
developed muscle bands running perpendicularly to the margin and ending abruptly at 
a short distance from it so as to form a sort of boundary zone surrounding the remain- 
ing part of the mantle. The siphons are strongly muscular. 
The tentacles are simple, filiform, and numerous; they are not all of one size 
and are arranged irregularly. 
The branchial sac is rather delicate, and slightly plicated longitudinally. The 
internal longitudinal bars are numerous but very thin, and bear at the points of crossing 
