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Show 1889] LAND-SHELLS FROM BORNKO. 343 to the penultimate whole, curved downward and pointed ; rounded, the last leaving the penultimate at the sutural tube 7 millim. from the aperture; peristome double, the outer thin and much expanded at right angles to the whorl. Size: maj. diam. 23*0, min. 16*80; alt. axis 4*0; body-whorl alt. 9*5 millim. Hab. Borneo (coll. Hungerford). This shell is in Dr. Hungerford's collection and was sent to him from the Molu Hills by Mr. Boxall. 29. RHIOSTOMA IRIS, n. sp. Shell depressedly turbinate, openly and perspectively umbilicated ; colour deep ochre, with regular zigzag bands of ruddy brown crossing the whorls ; spire just raised above the last whorl; apex blunt ; suture well impressed; whorls 4, rounded, the last separated from the penultimate for about 5 millim. from the aperture, where the sutural tube rises, this is short, horizontal, and directed forwards ; aperture oblique ; peristome double, continuous, inner simple, outer expanded at right ansles to the body-whorl, more particularly on the outer margin, and increasing to a crinkled expansion or wing on the upper margin and directly in front of the sutural tube, this wing terminates abruptly on the columellar side. Size: maj. diam. 18*25, min. 14*0; alt. axis 5*75 millim. Operculum with a smooth central spot, multispiral, shelly, flatly concave. Hab. Borneo (coll. Hungerford). The exact locality where this shell was collected is not known to me, but it is distinct from all the other species with which I am acquainted. C Y C L O T U S , Swains. Dr. Ed. v. Martens, after separating the American forms under Troschel's genus Aperostoma, divides this genus (as represented in India and the Malay Archipelago) into four very distinct groups, based on the shell characters. The differences that exist are not sufficient to found new subgenera, and I follow his grouping nov because it is certainly an aid to the identification of the species. 1st Group. Cycloti pterocycloidei. Shell of depressed form, widely umbilicate, with the peristome reflected, forming a more or less well-developed wing above. 30. CYCLOTUS BOXALLI, n. sp. (Plate XXXVI. figs. 4, 4 a.) Shell dextral, discoid, very openly and perspectively umbilicated ; sculpture a thick epidermis with fine lines of growth ; colour rich dark madder-brown ; spire papillate ; apex slightly raised above the last whorl; suture deeply impressed ; whorls 5, well rounded, regularly increasing ; aperture oblique, circular; peristome double, inner very thin, simple, continuous on columellar margin with the outer lip, this last gradually expanding and reflected on the lower and outer 23* |