1S94.] LAND-SHELLS FROM THE SAMUI ISLANDS. 147 



columellari suhohsoleto, nodiformi, dentibus in margine externo 

 approximatis subcequalib us. 

 Diam. 10'5, alt. 7 millim. 



By the flatter spire and the stronger distortion of the last whorl 

 to the right this form appears at first sight to be very different ; 

 and as there are some differences in the dentition as well, I feel 

 almost inclined to separate it specifically. Having only one speci- 

 men of the variety and but two of the type, I leave this question 

 for further study. 



2. Streptaxis mirificcs, sp. no v. (Plate XVI. figs. 1, 2.) 



T. umbilicata, depressa, subtilissime striatula, nitens, pellucida, 

 hyalina. Anfraetus 5|, planulati, superi spirant regularem 



perplanam apice fere immerso effieientes ; penuUimus ad peri- 

 pheriam acute carinatus ; ultimus maxime distorlus, valde 

 excentricus, basi peculiariter impressus, ad aperturam valde 

 compressus, subttis subacute cristatus, sat cleflexus. Apertura 

 maxime obliquci, perangusta, irregulariter cordiformis; peristoma 

 sat expansion, albo-labiatum. Lamella parietalis peralta, valida, 

 longe intrans, superne bicruris, utrinque in ccdlum parietalem 

 desinens. 

 Diam. 9, alt. 4 millim. 



A fine new species of the group of S. exacutus, Grid., and S. Jian- 

 leyamis, Stol., both from Moulmein, distinguished by the entirely 

 plane spire with almost immersed centre, the bifid parietal lamella, 

 the compressed cordiform aperture, &c. 



3. Streptaxis roebeleki, sp. nov. (Plate XVI. figs. 3, 4.) 



T. aperte umbilicata, depressa, subtiliter arcuatim costulata, tenuis, 

 pellucida, hyalina. Anfr. 6, convexiusculi, sat lente accrescentes, 

 superi spirant subregularem depresso-conoideam effieientes ; pen- 

 ultimug vix, ultimus paullum distortus, basi subinjlatus, glabra- 

 tus, pone aperturam coarctatus. Apertura diagonalis, truncato- 

 elliptica ; peristoma sat expansum rejlexiusculum, albo-labiatum, 

 margine externo prof unde sinuato, ad insertionem subito attenuato, 

 recedente. Lamella parietalis valida triangulariter elevata, 

 dentibus 3 lamelliformibus in margine externo et basali et nodido 

 in columella oppositis. , 



Diam. maj. 8 - 5, min. 7, alt. 5 - 25 millim. 

 Forma major : diam. maj. 10, min. 8, alt. 5'5 millim. 

 Forma minor : „ 7*5 „ 6, „ 3'75 „ 



I find no recorded form of Streptaxis with which this interesting 

 species could be united. According to the rather meagre descrip- 

 tion, 8. elisa, Gld. (Proc. Bost. Soc. vi. 1856, p. 12 ; Pfr. Mon. Hel. 

 v. p. 448), of the Mergui Archipelago, must be somewhat similar, 

 but is larger, has one whorl more, the whorls are angulate or 

 carinate, and there are two parietal lamellae. Both species are by 

 their depressed and almost regular form, with very little distortion, 

 rather isolated among the Asiatic Streptaxes ; in the somewhat 



10* 



