48 HELICIILE. 



fasciata ; spira conica, obtusula ; anfr. 4| convexiusculi, rapide 

 accrescentes, ultimus antice descendens, peripheria obsoletissime 

 subangulatus ; apertura diagonals, oblique oblonga, intus alba ; 

 perist. hepaticum, marginibus callo nigro-castaneo nitido, intrante 

 junctis, supero leviter arcuato, expanse et reflexiusculo, columellari 

 declivi, piano, perdilatato, adnato. 



" Diam. maj. 38, min. 30, alt. 27 mill." (Albert.) 

 Nearly allied to A. luxmastoma, but appears to differ in being 

 less solid, having more convex wborls the base being decidedly 

 more convex, but not gibbous behind the columellar margin as 

 in hcemastoma, while the lip is reflexed but not expanded as in the 

 latter. The numerous narrow encircling bands also distinguish 

 it. A specimen, however, acquired by me from the H. Nevill 

 collection, exhibits two blackish-brown zones above the periphery 

 one narrow, under the suture, and the other broad, separated 

 from the first by a narrow light zone and extending to the 

 periphery as often observed in hcemastoma. In addition there 

 are below the periphery five more or less distinct linear bands. 

 These zones and bands may be indicated by the following formula : 

 1(23 ) 3 ** 55 . This shell is well represented by figs. 3 and 4 on 

 plate 32 B of Ferussac's work, except that these show an additional 

 linear band between the two dark zones. 



When describing the shell, Albers gave the Malay Peninsula 

 as habitat. This was already called in question by Pfeiffer in 1855, 

 while in 1859 he definitely indicated Ceylon as its origin. 



62. Acavns prosperus, Albers. 



Helix prospera, Albers, Malak. Blatt. iv, 1857, p. 93, pi. 1, figs. 7, 

 8 ; Hanley & Theobald, Conch. Ind. 1876, pi. 150, fig. 4. 



HeUx (Acavus) prospera, Martens, Die Heliceen, ed. 2, 1860 

 p. 172. 



Helix (Macroon (Acavus)) prospera, Pilsbry, Man. Conch, ser. 2, 

 vi, 1890, p. 80, pi. 17, figs. 14, 15. 



Acavus prosperus, Pilsbry, ibid, ix, 1894, p. Io4. 



Original description : " Testa imperforata, orbiculato-globosa, 

 solida, distincte striata, unicolor castaneo-purpurascens ; spira 

 parum prominens, globosula, vertice rosea ; anfractus 4 convexi, 

 modice accrescentes, ultimus antice non protractus, mediocriter 

 descendens ; apertura obliqua, oblongo-lunaris, basi rotundata, 

 intus lactea ; peristoma purpureum, expansum, breviter reflexum, 

 margine dextro medio innexiusculo, superne arcuato, columellari 

 stricto, dilatato, vix excavato, sensim in basalem transeunte ; 

 paries aperturalis callo purpureo obductus. 



"Diam. maj. 44, min. 34, alt. 25 millim." (Albers.) 



Hob. Ceylon. 



It is stated to differ from A. hcemastoma in being more globose, 

 the depressed spire, rounded above, not conical, and in being 

 unicolorous. 



