HELIX-ACAVUS. 83 



The reverse or back of the reflected lip is blackish-brown, not light 

 as in the superba and roseolabiata. The surface is more or less prom- 

 inently corrugated on the back of the body-volution by obliquely de- 

 scending folds, generally less regular than in my figure 47. 

 Alt. 44, diarn. 52 mill. Alt, 36, diam. 44 mill. 



Ceylon. 



H. grevillei PER. Proc. Zool. Soc. Loncl. 1856, p. 387 ; Mono- 

 graphia iv, p. 105 ; Novitates Conch, i, t. 30, f. 6, 7. HANLEY & 

 THEOBALD, Conch. Indica, t. 127, f. 7. 



This form has the same angular contour shared by superba and 

 roseolabiata. The surface is more corrugated by oblique folds than 

 the majority of specimens of If. superba, but not more than the 

 rougher examples of that form before me. The lip and parietal 

 band, as well as the greater part of the columellar plate are black, 

 as in If. phoenix. 



I may safely say that H. grevillei is not more distinct from the 

 typical superba than roseolabiata is ; and the three constitute in my 

 opinion nothing more than varietal manifestations of a single spe- 

 cific type. 



Group of H. waltoni Rve. 



H. WALTONI Reeve. PI. 18, figs. 20, 21. 



Shell globose-depressed, the spire very low and small ; lip ex- 

 panded and re volute, not thickened, blackish-brown. 



The shell is of a globose form, much depressed, and transversely 

 inflated so that it is oblong seen from above or below. The spire 

 is small and short, very obtuse; whorls about 3f, the first 3J form- 

 ing the embryonic shell, which is separated from the after-growth 

 (of a little over one volution) by a distinct line and a change of 

 color, the nucleus being darker than the part following. The last 

 whorl is much inflated, and descends deeply in front. The color is 

 pinkish, banded with chestnut-brown ; the bands rather wide, 3 to 6 

 in number, fading into the ground-color at their edges. The whole 

 shell is covered with a very thin yellowish epidermis, which comes 

 off in angular patches and flecks, leaving pinkish markings; or remain- 

 ing on these tracts becomes separated from the shell substance, and 

 appears as white or cream colored angular hydrophanous patches. 

 The surface is obliquely striate, and under a lens is seen to be cut 

 into granules in places by fine incised spiral lines. The aperture is 

 very oblique, of a lovely pink tint inside ; the broadly reflected per- 



