1889. | LAND-SHELLS FROM BORNEO. 343 
to the penultimate whole, curved downward and pointed ; whorls 4, 
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. 
PA 9 
Rt. 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 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°74 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 now 
because it is certainly an aid to the identification of the species. 
Ist Group. Cycloti pterocycloidet. 
Shell of depressed form, widely umbilicate, with the peristome 
reflected, forming a more or less well-developed wing above. 
(yy 148% 30. CycLorus BOXALLI, nb. 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 
23* 
