178 GASTROPODA. [PectinibrancJiia. 



KEY TO SPECIES. 



A. Spire of shell the same height as that of the aperture, or but 



little higher. 

 a. Whorls spirally lirate. 



1. Base bicarinate . . . . . . . . bicarinatum. 



2. Subobsolete spiral striae on base only . . . . pannosum. 



3. Regularly decussate, hairs at intersections . . cytora. 



4. With membranous radiate plaits, getting gradually 



more distant on approaching the aperture . . Hedleyi. 



tin. Whorls without spiral sculpture. 



1. With irregular radiate threads ; rufous or brown . . lignarium. 



2. With regular growth-lines only ; horny . . . . Studeri. 



B. Spire considerably higher than the aperture. 



. Last whorl angled or subangled. 



1. No sculpture, except growth-lines . . . . calvum. 



2. Spirally lirate . . . . . . . . . . pallidum. 



an. Last whorl rounded. 



b. Perforation covered. 



1. Height of shell less than 2 mm. . . . . torquillum. 



2. Height of shell more than 2 mm. . . . . Chiltoni. 

 bb. Subperforate, perforation partly open . . . . fasciatum. 



Subgen. 1. CYTORA, Kobelt, 1902. 



Cytora, Kobelt and Moellendorff, Nachrichtsblatt Deutsch. Malak. Gesellsch., 

 1897. 85 (name only). Type: L. cytora. (Iray. Cytora. Kobelt, in 

 " Das Tierreich," 10. Lief., 1902, (i5. Murdochia, Ancey, J. de Conch., 

 xlix, 1901, 24. 



Shell small, thin ; epidermis usually smooth, rarely with mem- 

 branous processes or hairs ; sutural notch of the peristome slight. 

 Operculum horny, not calareous, with subcentral nucleus and few 

 volutions. 



1. Lagochilus bicarinatum, Suter, 1907. Plate 11, fig. 10. 



Lagochilus bicarinatum, Suter, P. Mai. S., vii, 1907, 238, pi. 22, f. 10. 



Shell small, turbinate, umbilicate, base bicarinate. Sculpture con- 

 sisting of fine, subequidistant, blunt, incremental axial striae, 2 carinse 

 on the base, the upper one arising from the junction of the outer lip 

 with the whorl, and terminating a little below the middle of the outer 

 lip ; the lower rib departs from the middle of the body- whorl between 

 the margins of the aperture, and ends at the distal side of the basal 

 lip ; no spiral striation is present. Colour fulvous to brown. Epi- 

 dermis thin, slightly shining ; there may be axial membranaceous 

 plaits, but in the only specimen before me they have evidently been 

 lost. Spire conical, of the same height as the aperture, apex obtuse. 

 Protoconch consisting of 1 whorl, which is globular and smooth. Suture 

 deeply impressed. Aperture circular. Peristome slightly reflexed and 

 callous, but sharp ; notch at the suture very indistinct. Columella 

 concave, partly concealing the umbilicus, which is deep and of about 

 i mm. diameter. The umbilical tract immersed and margined by the 

 lower carina. Operculum thin, circular, multispiral, with membranous 

 outer and central processes. 



