MOLLUSCA OF INDIA. 193 



somewhat of a surprise to me. It was a satisfaction to discover 

 at last the type of their anatomy, and that they are closely related 

 to, and can be placed in, the genus Philalanlca. 



Philalanka thwaitesi, Pfr. (Plate CXIl. figs. 1-1 c.) 



Helix tJmaitesi, Pfr. P.Z. S. 1853, p. 125. 



Helix nuwara, Jousseaume, Mem. Soc. Zool. France, vii. p. 10, 

 pi. iv. fig. 3. 



Helix suavis, Jousseaume, loc. cit. 



Helix tJiivaitesi, Pt'r. Mori. Hel. vol. iv. p. 50 ; Reeve, Conch. 

 Icon. fig. 1336 ; Hauley, Conch. Ind. p. 52, pi. cxxviii, figs. 7-10. 



Macrochlamys (sec. D) thtuaitesi, Theob. Suppl. Cat. p. 19. 



Microcystis suavis, 0. Collett, Journ. R. Asiat. Soc. Ceylon, 

 vol. XV. (1897). 



Original description ; — " Testa aperte perforata^ convevo-depressa, 

 striatula, niticla, cereo-hyalina ; spira hreviter conoidea, obtv^ula : 

 sutura profunda, siihmarginata ; anfr. 6|, convexi, arete convoluti, 

 ultimus non descendens, basi injlatus ; apertura verticalis, lunaris ; 

 perist. rectum, acutum, margine columellari arcuatim oblique de- 

 scendente, ad perforatione vix dilatato. 



" Diam. maj. 5, min. 4|, alt. 3 mill. 



" Habitat in Insula Ceylon. 



Shell. Seven faint longitudinal lines can be counted on the first 

 whorl. 



Animal. This was beautifully preserved in the formalin — a 

 medium which seems eminently adapted for minute forms. The 

 foot is long and narrow, pointed behind, and presents no mucous 

 gland. The mantle-margin was rather swollen and indistinct, but 

 there were no shell-lobes. The jaw and radula were extracted 

 quite perfect. The first (figs. 1 a, 1 b) is thin and delicate, poly- 

 placognathous, slightly curved, consisting of 12 quadrate plates, 

 slightly overlapping each other on the side; the two outermost 

 very small and narrow. The teeth of the radula (fig. 1 c) are 

 arranged : 



22 . 1 . 8 . 1 . 8 . 1 . 22 

 31 . 1 . 31 



The central tooth is tricuspid, its side cusps small. The admedian 

 have one long tooth, with a side tooth rather remote from it 

 on the outside ; this in the ninth is small. The laterals at 

 once differ at the tenth tooth in having two nearly equal, sub- 

 oblique, close-set, parallel teeth, and one shorter, contiguous to 

 them outside ; these pass into others, with three parallel very 

 straight teeth set oblique to the quadrate plate, the outer one 

 slightly shorter than the two inner, finger-like in form. Towards 

 the margin the teeth become very minute, only two generally to be 

 seen, and in about four of the outermost only the oblong narrow 

 plate can be made out. 



Genitalia of the same type as in P. secessa. The male organ is a 



