160 OPEAS, TONKIN. 



its peripheral keel. The imperforate axis also is unusual in 

 this genus, to which the species is referred with some doubt. 



39. 0. FAGOTI Mabille. 



Shell high-subpyramidal. Slender, thin, rather fragile, 

 subpellucid, pale buff, rather glossy, ornamented with dense, 

 arcuate, subcostulate striae. Spire long, acuminate, the apex 

 obtuse, mamillate, glossy, smooth. Whorls 10, gradually and 

 regularly increasing, separated by an impressed, very min- 

 utely tuberculate suture; the last whorl larger, nearly one- 

 third the total length, slowly descending to the aperture, 

 compressed basally. Aperture vertical, oblique, narrowed; 

 columella slightly arcuate, a little thickened, reaching to the 

 base of the aperture; peristome thin, unexpanded; margins 

 joined by a very thin callus, forming an inconspicuous um- 

 bilical crevice. Outer margin slightly attenuate. Length 21, 

 diam. 6 mm. (Mabille). 



Tonkin (Balansa). 



Opeas fagoti MAB., Moll. Tonk. Diagn. p. 10 (May 14, 1887; 

 Bull. Soc. Mai. France iv, p. 106. 



This unfigured species may be a Prosopeas. 



40. 0. HEDEIUM Mabille. 



Shell minute, perforate, long-turrite, thin, fragile, corn- 

 eous, slightly shining, densely arcuately hair-striate ; apex 

 minute, glossy, rather acute. Whorls 9, gradually and regu- 

 larly increasing, a little convex, separated by an impressed, 

 obscurely marginate and very minutely granulate suture, the 

 last whorl subcylindric, inflated, scarcely one-third the length 

 of the shell, a little descending to tb aperture. Aperture 

 vertical, roundly arcuate at the base ; columella subarcuate, a 

 little thickened, calloused, extending to the base ; outer margin 

 nearly straight, columellar dilated, half covering the per- 

 foration. Length 15, diam. 3 mm. (Mabille). 



Tonkin (Balansa). 



Opcas hedeius MABILLE, Moll. Tonk. diagn., p. 11, 14 May, 

 1887; Bull. Soc. Mai. France iv, p. 105. --Opeas hedenes 

 Mabille, FISCHER, Catal. et Dist. Geogr. des Moll. terr. etc. 



