MANUAL OF THE MOLLUSCA. 



Duminyi,* Eequien; lateral cini, 3 on eacli side (sometimes 4 

 on one side, and 3 on tlie otter. — Clarke). Fossil, in the Coral- 

 line Crag ; Britain ; Catania. Living, Britain ; Mediterranean. 



TrochococMea, Klein. Spii'e moderately raised ; base, slightly 

 umbilicated in the adult, perforated in the young, pillar lip with 

 a strong tubercular tooth. Lateral appendages 3 to 4 on each 

 side. Example, T. lineatus, Da Costa. Britain, France, Spain, 

 Mogador. 



Ziziphinus, Leach. Spire pyramidal, base iniperforated ; 

 pillar lip notched or angulated at the lower part. Example^ 

 T. granulatus. Born. 7 species, Britain. 



Omphalius, Philippi. Type, Trochus yiridulus, Gmel. 

 Mazatlan. 



Shell with a spiral ridge surrounding the umbilicus, ending 

 in one or more tubercles on the columella. 



Distribution, 4 species. Mazatlan, China. 



Pyramis, Enida, 6rc. 



EoTELLA (see p. 265). 



Sub-genera. Isanda (I. coronata), Adams. Shell orbicular, 

 conical, pillar edge crenated ; whorls rounded ; axis umbili- 

 cated ; operculum orbicular, of many whorls. 



Chrysostoma, Gray. Tui'bo Nicobaricum, Gmel., related to 

 Isanda. Pillar edge callous ; operculum horny, spiral. 



Microthyca, Adams, differs from Isanda in its continuous peii- 

 stome and thickened outer lip. 1 species, Japan. 



Umhonella, Adams. Shell porcellanous, small, turbinated, 

 allied to Chrysostoma, but the aperture is circular, and the axis 

 imperforate. 1 species, Japan. 



Letjcorhyk^chia, Crosse, 1867. 



Etymology, leucon, white ; rhynchion, a beak. 



Type, L. Caledonica, Crosse ; inhabits under stones, New 

 Caledonia. 



Shell depressed, sub-discoid, umbilicated, polished, of few 

 ■uhorls; aperture rounded, not nacreous. A thick callositj' 

 arises from the front margin of the aperture and the columella 

 lip, and is continued as a free rostrated process over the um- 

 bilicus. Opsrculiun corneous, rounded, multispiral; nucleus, 

 central. 



• Adecrbis supranitida and A tricariuata are veneties. 



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