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PKOVISIONAL AID TO THE STUDY OF TASMANIAN MOLLCSCA. 



Sub-Genus Monilea. Swainson. 

 Shell orbicular, depressed, widely umbilicaled ; whorls encircled 

 by grooves, the last rounded ; umbilicus encircled by a 

 striated callus ; columella terminating anteriorly in one 

 or two tubercles. 



Sub-Genus Gibbttla. 

 Shell conoidal, umbilical ed ; umbilicus cylindrical or infundibuli- 

 form; whorls frequently tuberculated above, and with 

 channeled suture; columella sometimes terminating in 

 a tubercular tooth. 



Sub-Class Zizyphintjs. Gray. (Calliostoma.) Swains. 

 Shell trochiform, conical, not umbilkated ; last whorl angulated 

 and usually ribbed at the periphery ; aperture, quadran- 

 gular ; columella simple, oblique, often ending in a 

 tooth in front. 



Sub-Genus Thalotia. Gray. 



Shell ovate-turriculated, rather thick, not umbilicated ; whorls 



flattened, with revolving ribs, which are sometimes 



granular ; aperture, sub-rotund ; columella tuberculate, 



truncate in front ; outer lip rather thick, crenulated within. 



Sub-Genus Elenchus. Humphrey. 

 Shell elevated, conoidal, spire sharp ; whorls rather flat, smooth 

 polished, usually with distant revolving incised lines ■ 

 aperture sub-oval; columella with a tooth-like 

 projection in the middle ; outer lip thickened within. 

 Brilliantly coloured shells, but very pearly within 

 (used as ornamental necklaces by the Tasmanian 

 Aborigines). 



Sub-Genus Canthaeidus. Montfort. 

 Shell ovate, thin, outer lip acute ; the columella wants the 

 conspicuous tooth seen in Elenchus ; the whorls are 

 encircled by stria and not polished ; interior highly 

 iridescent. 



Sub-Genus Bankivia. Beck. 

 Shell subulate, with sharp spire, polished, bright coloured; 

 whorls smooth, flattened, without epidermis ; aperture 

 sub-ovate, rather large, not nacreous within ; columella 

 twisted, truncated in front ; outer lip simple, sharp. 



Sub-Genus Teochocochlea. Klein. 

 Shell elevated, turbiniform ; whorls bluntly angled at the 

 periphery, or with revolving carinas; outer lip thin, 

 smooth within; inner lip spreading, twisted, dentate 

 belcnv, no umbilicus. 





