MOLLUSCA OF INDIA. 11 
On the Subgenus Microcystina, with Descriptions of the 
Original and New Species. 
(Plate III.) 
This genus was first introduced, but without any description, by 
Prof. A. O. L. Mérch in his paper on the Shells of the Nicobar 
Islands, published in the ‘ Journal de Conchyliologie,’ October 1872, 
p. 311; in the same Journal for October 1876, p. 356, its characters 
are given—‘ a little notch, narrow and very deep at the columellar 
margin ;” and he compares it with molecula, Bs., from Burmah ; 
but I cannot detect in this last any resemblance save in form and 
polished surface. The columella is not similar*. At the same time 
(in 1872) we find Prof. Morch creating another subgenus, Litho- 
cystis, on a species named brunii by him; but no description is 
given, Helia gouldii, Pfr., miliwm, Martens, and cassidula, Bs., 
being quoted as similar in form. In 1876 (1. ¢. p. 357), Liocystis, 
we are told, differs from Microcystina by the columella being twisted 
in S-form and not notched, and by an unpolished surface f. 
The shell of W. rinkii is a small one, and the animal was not in 
a very perfect state, so that I am not able to give a very satisfactory 
description of its outer form, but it is sufficient to place it in a 
better position with regard to other genera. 
Animal. The right shell-lobe was distinguished, and a long nar- 
row left shell-lobe in two portions (fig. 3). The dorsal lobes were 
not made out. The extremity of the foot has a long pointed process 
above the mucous gland (fig. 4). The generative organs (fig. 5) were 
not all got at in a perfect state. The penis is long, with a slight 
short twist on the side next the vas deferens, and there is another 
rather swollen portion with a convolution lower down. The amatory 
organ, D, is also present. 
The odontophore (figs. 7 & 7a) I am enabled to describe much 
more minutely, as it was dissected out very perfectly, the dental 
formula being— 
Bh 4odOpDQvFor Lak 21385 to 40 
= 44 to 50.1. 44 to 50. 
The central tooth is very long and sharp-pointed, with two sharp 
well-developed cusps on either side; the next seven medials are also 
very clongate and sharp, with a single cusp on the outer lower 
margin ; in the eighth this is absent, being a plain unicuspid tooth ; 
the next, the ninth, is bicuspid, with the outer cusp slightly shorter, 
these two being of transitional form; then follow the series of bi- 
* Original description :--“ Les Microcystina sont caractérisés par une petite 
échancrure, étroite et assez profonde, 4 la columelle, qui montre de faibles 
traces d’une dent obtuse. La coquille est polie sur toute sa surface. L'Helix 
molecula, Benson, de Birmanie, parait trés-analogue.” 
+ Original description :—‘“ Les Liocystis different des Microeystina par leur 
columelle tordue en § et non échancrée, et par leur surface non polie,” 
B 
