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Show 1894.] LAND-SHELLS PROM THE SAMUI ISLANDS. 147 columellari subobsoleto, nodiformi, dentibus in margine externo approximatis subcequalibus. 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 specimen of the variety and but two of the type, I leave this question for further study. 2. STREPTAXIS MIRIFICUS, sp. no v. (Plate XVT. figs. 1. 2.) T. umbilicata, depressa, subtilissime striatula, nitens, pellucida, hyalina. Anfractus 5|, planulati, superi spiram regularcm perplanam apice fere immerso efficientes ; penidtimus ad peri-pheriam acute carinatus; ultimus maxime distorlus, valde excentricus, basi peculiariter impressus, ad aperturam valde compressus, subtus subacute cristatus, sat cleflexus. Apertura maxime obliqua, perangusia, irregulariter cordiformis; peristoma sat expansum, albo-labiatum. Lamella parietalis peralta, valida, longe intrans, superne bicruris, utrinque in callum parietalem desinens. Diam. 9, alt. 4 millim. A fine new species of the group of S. exacutus, Gld., and S. han-leyanus, 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 ROEBELENI, sp. nov. (Plate XVI. figs. 3, 4.) T. aperte umbilicata, depressa, subtiliter arcuatim costulata, tenuis, pellucida, hyalina. Anfr. 6, convexiusculi, sat lente accrescentes, superi spiram. subregularem depresso-conoideam efficientes ; pen-ultimus vix, ultimus paullum distortus, basi subinflatus, glabra-tus, pone aperturam coarctatus. Apertura diagonalis, truncato-elliptica ; peristoma sat expansum refiexiusculum, albo-labiatum, margine externo prof uncle sinuato, ad insertionem subito attenuato, reeedente. Lamella parietalis valida triangulariter elevata, dentibus 3 lamelliformibus in margine externo et basali et noclulo in columella, oppositis. Diam. maj. 8*5, min. 7, alt. 5*25 millim. Forma major: diam. maj. 10, min. 8, cdt. 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 description, S. 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* |