1871.] F. Stoliezka— Mfes en Terrestrial Mollusca. 221 



tooth, but this is not a constant character. In P.pinacis, the centre 

 tooth is larger and more of a shape similar to that of the lateral 

 teeth, which, however, in all the species retain distinctly the 

 helicoid character. 



Plectopylis achatina, Gray, pi. xv, figs. 1 — 3. 



Helix achatina, Gray apud Pfeiffer, Chein., &c. Hanley and Theob., Conch* 

 Indica, pi. xiii, fig. 1.* 



The two embryonal whorls are generally somewhat tumescent, 

 very finely punctated or scrobiculate, and of a pale yellowish or 

 whitish colour ; the third whorl is pale rufescent with the striaa of 

 growth distinct, in addition to which on the fourth whorl a spiral 

 striation appears, but it soon again becomes obsolete, while the 

 strise of growth continue to be well marked. 



Young shells are surrounded on the last whorl with three fringes 

 of hairy cuticle, above and below, and near the centre of the 

 whorl, which is conspicuously angular. The basal fringe at first, 

 disappears, then the median, and at last the upper one. 



The plication is one-third of the circuit of the last whorl distant 

 from the aperture. It consists on the inner lip of one oblique trans- 

 verse lamina, emitting at the base one short anterior fold, another 

 near the middle, extending up to the centre of the inner peris- 

 tome, at the upper end it is posteriorly bipartite, the lower branch 

 bending downwards across the inner lip and terminating with a 

 short rib directed backwards. At the base of the inner lip there 

 is besides a separate very thin rib which becomes obsolete before 

 it reaches the lower angle of the mouth. The outer lip has above 

 three longitudinal ribs, the innermost of which is thinnest and the 

 median posteriorly generally somewhat irregularly flexuous and 

 bifurcate, a large transverse lamina projects into the triangular 

 space formed by the inner lamina, and has a thin longitudinal rib 

 below it. 



This species is extremely common on all the limestone hills 

 about Moulmein. Among thousands of specimens not one dextrorse 

 variety was met with. The largest specimens I have seen mea- 



* A very inadequate figure of the species. The last whorl is unnecessarily 

 angular, the umbilicus too small, and the short fold at the basal angle of 

 the aperture far too strong. 



