Lao ma.] 



GASTROPODA. 



741 



allochroida. 

 Ariel. 



elaiodes. 



2. Group of Laoma conella. 



Shell subperforate, perforation more or less closed by the reflection 

 of the inner lip. 



KEY TO SPECIES. 



A. Shell with radiate riblets or rib-strise. 



a. Riblets 45 per millimetre, membranous ; spire about 1^ 

 times the height of the aperture . . . . 



aa. Riblets about 10 per millimetre. 



6. Riblets sharp, 10-12 per millimetre ; protooonch spirally 



striate; periphery convex ; diameter, 1-5 mm. .. 



bb. Rib-striate ; protoconch smooth ; periphery angled . . 



bbb. Radiate strife ; protoconch spirally lirate ; periphery 



convex ; diameter, 3 mm. . . . . 



aau. Riblets 2530 per millimetre . . . . 



B. Shell smooth. 



a. Periphery keeled, suture margined. 



b. Protoconch spirally striate ; 6 whorls : diameter, 



4-5 mm. . . . . Gheesemnni. 



bb. Protoconch smooth ; 5 whorls : diameter, 3-3-5 mm. conella. 

 aa. Periphery distinctly angled. 



b. Periphery lightly angled ; protoconch reticulate ; spire 



a little higher than the aperture . . . . elevata. 



bb. Periphery sharply angled : protoconch smooth ; height 



of spire less than that of the aperture . . . . jnl</nrntn. 



'ilia. Periphery convex, subangled in the young ; protoconch 



smooth. 



b. Spire H times the height of the aperture . . . . xnblucida. 



bb. Height of spire a little less than that of the aperture. . viridnln. 



4. Laoma allochroida, Suter, 1890. Plate 29, fig. 7. 



Hyalina allochroida, Sut., T.N.Z.I., xxii, 1889 (1890), 228, pi. 15, f. 14, a-c. 

 Laoma allochroida, Sut. : Pilsbry, Man. Conch. (2), viii, 63, pi. 23, f. 3-6. 

 L. (Phri.njnnthus) allochroida, Sut. : Hedley and Suter, P.L.8. N.S.W. (2), 

 vii, 649 ; Suter, J. de Conch., xli, 281. 



Shell minute, subglobose, subperforate, radially sharply costate, 

 corneous, thin, pellucid. Sculpture : Protoconch smooth, with rather 

 distant microscopic spiral lines ; the following whorls are radially 

 finely and sharply ribbed, 10 to 12 riblets per millimetre, they are 

 oblique, retractive, and somewhat arcuate on the periphery ; inter- 

 stices with numerous microscopic growth-lines, reticulated by less dis- 

 tinct spiral strise. Colour : The first three whorls are almost colour- 

 less, the penultimate corneous, and the last light fulvous. Epidermis 

 thin, lightly shining. Spire conoidal, of about the same height as the 

 aperture ; outlines broadly convex. Protoconch of 1^ whorls, flattish. 

 Whorls 5, convex, regularly increasing ; periphery and base rounded. 

 Suture deep. Aperture somewhat oblique, rotiuidly lunate. Peri- 

 stome straight, acute, margins convergent. Columdla very short, 

 arcuate. Inner lip reflexed and partly concealing the very narrow 

 perforation. 



Diameter, 1-5 mm. ; height, 1 mm. 



Animal unknown. 



