876 MOLLUSCA. 



Genus Helix, Linn. 



Sub-Genus Plectopylis, Benson. 



Helix (Plectopylis) andersoni, Blanf. 



Helix {Tledopylis) andersoni, Blanf., Proc. Zool. Soc, 1869, p. 448; Con. Indica, pi. 112, fig. 8; 

 Godwin-Austen, Proc. Zool. Soc, 1874, p. 612, pi. lxxiv,fig. 9 ; Nevill, I, c, p. 17. 



This remarkable form was not obtained on the Second Expedition ; it was 

 originally found at Bham6 and Hoetone. 



Sub-Genus Plectoteopis, Alb. 

 Helix (Plectotropis) tapeina, Bens. 



Helix tapeina, Bens., Journ. As. Soc, Bengal, 1H36, p. 352. 

 Helix [Plectotfopis] tapeina, Nevill, I. c, p. 17. 



The type specimens of Benson's S. tapeina are in the Indian Museum. Plate xv, 

 ^^. 6, of the Con. Indica well represents the form. It is distinguished from all other 

 allied species by the less oblique columellar margin, rounded and not angular at 

 the base as are all its varieties ; the keel at the periphery is acute. Typical 

 JS. tapeina is found abundantly at Cherra Punjee and in Assam. 



var. AKOUTONGENSis, Thcob. 



Helix aJcoutongensis, Ttieob., Journ. As. Soc, Bengal, 1859, p. 306 (not Con. Indica, pi. xv, fig. 4). 

 Helix [Flectotropis) tapeina, var. ahoutongensis, Nevill, /. c, p. 17. 



Only differs from the preceding by its more oblique columellar margin, more 

 acutely keeled periphery, slightly more open umbilicus, and more depressed spire. 

 I look upon this form as doubtfully separable from the next : the differences may 

 be merely perhaps incidental to individuals, and not even to local races. 



Dr. Anderson found this variety in Upper Burma, where it was very common. 



Axis 5, diam. 15 mm. 



var. ROTATORIA, Busch. 



Helix rotatoria, v. d. Busch., Phil. Icon., 1842 ; 11., p. 10, t. i, fig. 5 -, Mouss,, Moll. Java, pi. ii, fig. 8. 

 Heiix {Plectotfopis) tapeina, var. rotatoria, Nevill, I. c., p. 18. 



Only distinguished from the preceding variety by the less distinct or less exca- 

 vated sutures, by the very acutely keeled periphery, and by the very white, more 

 thickened, and less rounded margins of the aperture, showing within a distinct emar- 

 gination at the periphery. Plate xv, fig. 5, of the Con. Indica is an excellent 

 representation of this form ; it only differs from the figures of Mousson and Philippi 

 by its slightly more raised spire. 



