1894.] LAND-SHELLS FROM THE SAMUI ISLANDS. 151 



Fam. Stenogyrid^e. 



14. Opeas gracile, Hutt. 



15. Opeas eillforme, sp. nov. (Plate XVI. fig. 11.) 



T. rimata, gracillime turrita, tenuis, subtiliter et maxime confertim 

 striatula, nitens, pellucida, albida ; spira sensim attenuata, a/pice 

 obtusulo. Anfr. 7^, convexiusculi, lente accrescentes, sutura sat 

 impressa discreti. Apertura modice obliqua, anguste acuminato- 

 ovalis ; peristoma rectum, acutum, ntargine columellari incrassa- 

 tulo refiexo. 



Alt. 5 - 5, diam. 1*5 millim. 



I do not know any similar small and slender species o£ Opeas ; 

 the comparatively great number of whorls show that it is adult. 



Farm Pupid^e. 



16. Vertigo (Staurodon) moreleti, Brown. 

 Subsp. nov. SAMUI ANA. 



Differs from the Borneo and the Philippine-Island type (v. 

 Jahresb. Senckenb. nat. Ges. 1890, p. 252) in the slightly more 

 contracted shell and in the somewhat deeper groove behind the 

 outer peristome. 



17. Hypselostoma transitans, sp. nov. (Plate XVI. figs. 12, 

 13.) 



T. umbilicata, turbinata, oblique striatida , fusca. Anfr. 4,convexi, 

 spiram conicam apice papillari formantes ; idtimus paidlum 

 distortus, antice non ascendens, breviter solutus et porrectus, ad 

 peripheriam crista sat prominente, altera minore ad suturam 

 ductus, basi subgibber, circa umbilicum compressus. Apertura 

 parum obliqua, rotundato-tetragona; peristoma continuum, tenue, 

 expansum, haud rejlexum. Lamella parietalis validiuscula, antice 

 bifida, dentibus 2 in margine externo, 1 in basi et 1 in colu- 

 mella oppositis. 

 Diam. 2'75, alt. 2 - 66 millim. 



This peculiar shell presents an especial interest inasmuch as it 

 forms a decided transition from Hypselostoma to the Indian and 

 Chinese Boysidia, Ancey, of which Pupa hunanensis, Gredl., is the 

 type. As 1 have mentioned in the description of Hypselostoma 

 Jiungerfordianum (P. Z. S. 1891, p. 338), the genus appears to be 

 but an extreme development of the Boysidia type. Boysidia 

 strophostoma, Mdff., of South China, shows already a slight distor- 

 tion and detachment of the last whorl, which in the Samui species 

 is much less developed than in the other forms of the genus. 

 There can be no doubt, however, that it belongs to Hypselostoma, 

 with which it has the peculiar quadrangular shape of the last 

 whorl and the dentition of the aperture in common. H.cnssei, 

 Mor., of Tongkin seems to connect it with the other Malayan 

 species. 



