78 HELIX-ACAVUS. 



Group of H. ivaltoni. Shell depressed-globose, oblong, spire 

 very short and obtuse, scarcely projecting above the body-whorl. 

 The surface retains a thin epidermis, deciduous in places, not con- 

 cealed in life by any foreign growth. There are numerous more or 

 less perceptible low girdles on the shell, easily seen when it is worn. 

 The post-embryonic growth consists of only one whorl, or a little 

 more or less. H. ivaltoni and H. skinner i are the only species of this 

 type. 



Group of H. hcemastoma Linn. 



H. H^MASTOMA Liniie. PL 18, figs. 22, 23, 24, 25. 



Shell globose-conical, white, brown above and usually brown 

 around the umbilicus ; aperture very oblique ; columella not trun- 

 cated where it joins the basal lip. 



The shell is solid and opaque, with rounded periphery and co- 

 noidal spire. It is porcelaneous white, but dull, not polished when 

 in a natural condition ; the whole surface above the periphery is 

 usually of a reddish-brown hue, becoming paler of a brownish-flesh- 

 color on the embryonic three whorls, and pink on the inner two ; at 

 and below the periphery there is a white zone, which covers the base, 

 or is limited by a brown tract upon the umbilical region ; the suture 

 is often edged by a white line. The surface has rather rude but in- 

 conspicuous lines of growth, and under a strong lens is seen to be 

 covered by a dense minute pattern of incised criss-cross scratches ; 

 the embryonic whorls have radiating subregular stride, cut by sub- 

 obsolete spiral engraved lines. Whorls nearly 5, convex, the last 

 flattened and sloping above, a little descending in front. Aperture 

 very oblique, oblong-truncate, white inside, showing faintly the bands 

 of outer surface. Entire peristome broadly reflexed, of a bright 

 pinkish-red color typically ; columellar margin long, oblique, very 

 broadly expanded and aduate to the base, flat, with a curved exca- 

 vation at the place of the umbilicus ; parietal wall covered by a 

 heavy callus of the same color as the lip. 



Alt. 37, diam. 43 mill. 



Ceylon. 



Helix hcemastoma LINN. Syst. Nat. edit, x, p. 773. PFR,, Mono- 

 graphia i, p. 247. REEVE, Conch. Icon., f. 366. HANLEY THEO- 

 BALD Conch. Indica, t. 127, f. 2 and of authors generally. H. 

 hcematrayus BORN, Ind., p. 400. H. melanotragus BORN, Ind., p. 

 400 ; Test. Mus. Ca?s. Yindob., p. 388. H. senegalenms Encyc. 



