60 ACHATINID^. 



striate or costulate ; aperture oval, short, about one-third or 

 one-fourth the length of the shell ; cohimella arcuate, abruptly 

 truncate ; peristome simple, acute. A. cyano stoma, Ruppell, 



PERiDERis, Shuttleworth, 1856. (Corona, Albers [pt.], 1850.) 

 Shell imperforate, ovately conical or oblong, apex papillary, 

 shining, striate, decussated by very minute spiral lines, epidermis 

 very thin ; whorls 6-7 , the last usually obsoletely angulated ; 

 suture wrinkled, marginate ; aperture short, suboval, columella 

 slightly twisted, obliquely subtruncate ; peristome simple, acute. 

 A. balteata, Gould (xcviii, 41). 18 sp. West Africa. 



LTMicoLARiA, Schum., 1811. Shell perforate, conically or 

 turreted oblong, last whorl shorter than the spire ; aperture 

 oblong, suboval ; columella vertical, protracted at the base ; 

 peristome simple, thin, straight, columellar margin dilated, arcu- 

 ately reflexed. L. JEquatoria, Rve. (xcviii, 42). 31 sp. Africa. 



PSEUDACHATINA, Albcrs, 1850. Shell solid, oval, turriculated ; 

 whorls eight or nine, the last obtusely angular at the periphery, 

 and exceeding half the length of the shell ; columella subtortu- 

 ous, a little arcuated, truncate-tuberculate below ; aperture oval ; 

 peristome thick, slightly reflected ; lips united by a callosity. 

 F. Downesii, Gray (xcviii, 44). 7 sp. W. Africa. 



COLUMNA, Perry, 1811. Shell always sinistral, mvich elongated, 

 decussated, whorls oblique ; constricted at suture ; apex obtuse; 

 columella callous, spirally twisted, truncate at base ; peristome 

 simple, sharp. G. flammea, Martyn (xcviii, 46). 4 sp. W. 

 Africa. Fossil Achatinse occurring in the eocene of Upper 

 Missouri, and in the Paris basin, are referred to this group. 



CHiLONOPSis, Fischer de Waldheira, 1848. Shell bulimiform, 

 thick ; aperture ear-shaped, both lips greatly thickened, the 

 columellar lip tuberculate above, obliquely truncate below. 

 Bulimus auria-vulpiyia, Chemn., which occurs subfossil in the 

 island of St. Helena, is the type of this group. 



Stenogyra, Shuttleworth, 1850. 



Syn. — Sira, Schmidt, 1855. Subulina, Adams, 1855. 



Distr. — 250 sp. World-wide, tropical and temperate regions. 



Shell elongated, turriculated, whorls numerous, apex obtuse 

 or truncate ; aperture oval, small, columella thin, straight ; 

 peristome simple, sharp. 



Median tooth of the radula very small ; jaw thin, feeblj'- 

 arcuated, vertically plicate. 



OBELiscus, Beck, 1837 (= Stenogyra, restricted). Shell long, 

 imperforate, elongate-turreted, scarcely shining ; whorls 10-18, 

 last about one-fourth the total length ; columella straight, not 

 truncate; peristome simple. >S. oheliscus,, M.ov\c. (xcix, 31). 

 38 sp. West Indies, Central and South America, Natal, Philip- 

 pines, etc. 



