1889 ] LAND-SHELLS FROM BOKNKO. 



343 



to the penultimate whole, curve;! downward and pointed; whorls -4, 

 rounded, the last leaving the penultimate at the sutiiral tuhe 7 milliin. 

 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\i millim. 



Hab. Borneo (coll. Htmfferford). 



This shell is in Dr. Hungerford's collection and was .sent to him 

 from the Molu Hills by Mr. Boxall. 



^fy, 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 angles to the body-whorl, more particularly on 

 the outer margin, and increasing to a crinkled e.xpans-ion 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. 18-2.'i, min. 14-0; alt. axis .^v^i 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. 



Cyclotus, 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 non 

 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. 



Al^m^"^ 30. Cyclotus boxalli, n. sp. (Plate XXXVI. figs. 4, 4 a.) 



Shell dextrai, 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, regu- 

 larly 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 



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