250 Records of the Indian Museum. [VOL Ne 
Thordisa annulata, sp. nov. 
One specimen from the Andamans. It is much bent, but 
about 25 mm. long and 14 mm. broad. The general colour of 
the dorsal surface is yellowish white, diversified with strongly 
contrasting brown rings. The general texture is soft, and the 
whole dorsal surface is covered with soft papille, about I mm. 
high in the central area and smaller near the edges. ‘The openings 
for the rhinophores and branchiz are also surrounded by small 
papilla. A certain number of dorsal papillae have their bases 
enclosed by perfect or imperfect brown rings. The rest are colour- 
less. These rings are more numerous and more regular at the 
sides of the visceral mass, where they form two lines on either 
side. They are also numerous at the anterior and posterior ends 
of the mantle margin. But in the mid-dorsal space they are 
faint and imperfectly formed. On the underside of the mantle 
are a few scattered deep brown spots. The branchiz are six, 
tripinnate and greyish. The anterior portion of the foot is con- 
tracted, but appears to be grooved and notched. The tentacles 
are represented by two roundish lumps. 
There is no labial armature. The radula is crowded and 
rather confused, but the formula is about 35 %50.0.50. Most of 
the teeth are hamate, rather tall and thin, decreasing towards the 
centre, the first six or so on either side of the rhachis being quite 
low with long bases. At the outer ends of the rows the last five 
teeth are small, very transparent, and difficult to see. Often they 
are merely jagged or serrulate, but in some rows, at any rate, the 
last three teeth bear a tuft of fine hairlike denticles. 
The stomach is small and lies wholly outside the liver. The 
cesophagus and intestine are disposed so as to form an apparent 
circle. The liver is of a deep chocolate-brown, but its whole 
surface is covered by the white hermaphrodite gland, which is 
deeply channeled in many places and not even. 
The genitalia were rather hardened, and few details could be 
ascertained, but it was clear that the verge is provided with a very 
large and striking armature, consisting of scales bearing conical 
spines of considerable size as in Platydoris. Near the tip there 
are two rows of these scales oniy. On the lower part of the verge 
(and perhaps in the vas deferens) there are as many as twelve 
rows, but the spines are not quite so large and rather elongate. 
It is not easy to fix the genus of this form, for it combines 
(1) rings, like those found in Diaulula sandiegensis, (2) pectinate 
marginal teeth, as in Thordisa, (3) a genital armature, as in Garga- 
mella. I call it Thordisa, simply because that is the oldest of the 
three genera (1877), and the most likely to survive as a name, if as 
a result of further investigation several of Bergh’s genera are 
amalgamated. 
