528 MR. G. F. ANGAS ON SHELLS FROM MADAGASCAR. [June 5, 



light purplish brown, becoming darker behind the lip, partially 

 covered with a pale straw-coloured epidermis ; spire depressed, 

 whorls 4, rapidly increasing, somewhat convex, the last very wide, 

 swollen, bluntly keeled, with a slight depression above the keel ; 

 aperture nearly horizontal, transversely lunately ovate, margined 

 within with a broad band of purplish black, interior pale lilac ; 

 peristome thickened, expanded, and reflected, edged with white ; 

 margins approximating and joined by a callus. 



Diam. maj. 1 inch 8 lines, min. 1 inch 3| lines, alt. 9 lines. 



Hab. Ekongo, S.E. coast of Madagascar. 



This interesting shell may at once be distinguished from H. sepvl- 

 chralis and its allies by its elaborate sculpture, and by the expanded 

 form of the aperture. 



Helix ekongensis, n. sp. (Plate LIV. fig. 4.) 



Shell minutely umbilicated, depressedly globose, very thin, the 

 oblique lines of growth crossed by exceedingly fine, close-set, con- 

 centric lines, pale horn-colour, with one narrow brown band above 

 the suture on the upper whorls, and two on the last whorl, one on 

 either side of the periphery ; spine depressedly conical, apex obtuse ; 

 whorls 6, flatly convex, the last not descending ; aperture oblique, 

 lunately ovate ; outer thin, simple. 



Diam. maj. 11 lines, min. 10 lines, alt. 6 lines. 



Hab. Ekungo, S.E. Madagascar. 



Helix balstoni, n. sp. (Plate LIV. fig. 5.) 



Shell imperforate, depressedly conoidal, thin, sculptured all over 

 with extremely fine, close-set, engraved lines that cross each other 

 obliquely both ways, giving the surface a delicately shagreened ap- 

 pearance under the lens, fulvous horn-colour throughout ; spire 

 depressedly conical, apex somewhat obtuse ; whorls 6, flatly convex, 

 the last sharply keeled at the periphery, not descending in front ; 

 base convex, shining ; aperture oblique, quadrately ovate ; outer lip 

 thin, simple. 



Diam. maj. 1 inch 2 lines, min. 1 inch, alt. 7 lines. 



Hab. Interior of Madagascar. 



In form, this species greatly resembles Helix semidecussata, Pfr., 

 from India ; but the sculpture of the whorls is quite different, and 

 is remarkable for its extreme delicacy and beauty. 



At the request of Mr. Edward Bartlett I have named this shell 

 after Mr. W. E. Balston. 



Physa madagascariensis, n. sp. (Plate LIV. figs. 2 a, 2 6.) 



Shell sinistral, perforate, thin, longitudinally plicately striated, the 

 striae being more regular on the upper whorls, horn-coloured ; spire 

 obtusely conical, apex blunt ; whorls 4^, convex, the last large and 

 inflated ; aperture ovate, narrower above ; outer lip thin, simple, 

 arcuate ; columella with a broad callus expanded over the umbilical 

 region. 



Alt. 8 lines, diam. 5 J lines. 



Hab. Okongo, S.E. Madagascar. 



