254 



overhanging pointed process as in that genus. In the genitalia it 

 differs from Macrochlamys in that the male organ is simple and 

 the retractor muscle is attached without any caecum. The dart- 

 sac was observed in M. rinlci, but not in M. bintennensis. In the 

 former it was shorter than the spermatheca, which was an elongate 

 sac. 



Further detailed examination of the animal of the Andaman and 

 Nicobar species is desirable. 



A. Species from Nicobar Islands. 



389. Microcystina rinki, Mdrch (Nanina), Journ. Conchyl xx, 1872, 

 p. 311 ; xxiv, 1876, p. 356 ; Pfr. (Helix) Mm. Hel vii, 1876, 

 p. 142; Nevill, Nanina (Microcystis), Hand-l. i, 1878, p. 39; 

 Godwin-Austen, Mol Ind. i, 1882, p. 12, pi. 3, figs. 1-7 (shell and 

 anatomy). 

 [ Vide fig. 81, B-B 3, p. 242.] 



Shell very narrowly and obtectly perforate, convexly depressed, 

 thin, smooth, highly polished, with fine, longitudinal, parallel, 

 microscopical striation above and below ; brownish horny, rather 

 paler and whitish beneath ; spire convexly conoid, suture impressed ; 

 whorls 5, convex, the last descending slightly and gradually towards 

 the mouth, rounded at the periphery, tumid beneath ; aperture 

 oblique, lunate ; peristome thin, columellar margin oblique, thicker, 

 and rather broadly reflected, with a salient angular process nearly 

 closing the perforation. 



Major diam. 5*5, min. 5, height 3'5 mm. 



Hub. The Nicobar Islands. Recorded from Great Nicobar 

 (Morch\ Little Nicobar (Busch), Katchal Camorta, Car Nicobar, 

 and Teressa (de Ecepstorff}. 



In the animal the left dorsal lobe is in two parts. The dart-sac 

 is present. The teeth on the radula are 35 to 40 . 2 . 7 . 1 7.2. 

 35 to 40, or about 47 . 1 . 47 : the inner laterals broad, elongate, 

 and sharp, each with one cusp on the outside, none inside ; outer 

 laterals each with two terminal blunt cusps. 



B. Species from Andaman Islands. 



390. Microcystina moerchiana, Godwin-Austen (Nevill, MS.), Mol. 



Ind, i, 1882, p. 13, pi. 3, fig. 9 (shell) ; ii. 1898, p. 47. 

 Microcystina hochstetteri, Godicin- Austen, A. M. N. H. (6) ii, 



1888, p. 57. 



Shell imperforate, conoidly depressed, thin smooth, highly 

 polished, very finely and closely striated longitudinally beneath 

 the microscope, brownish horny, paler beneath around the umbilical 

 region ; spire conoidal, apex obtuse, suture almost flat, scarcely 

 impressed ; whorls 5, slightly convex, the last not descending, 

 rounded at periphery, rather tumid beneath ; aperture very slightly 



