MANUAL OF THE MOLLUSCA. 



apex of embryonic sliell sliglitly twisted ; crown never pro- 

 minent, incurved, and nearly terminal, usually thin, with, an 

 opalescent hue. 



Animal. Mantle fringed at its edges with cirri ; gills not so 

 numerous as in Patella^ and forming a shorter plume, which is 

 interrupted over the head. 



Helcion lives on Laminarioe and sea-weeds of a similar kind, 

 and is therefore sublittoral. 



Distribution. Species few. but having an extensive range. 

 Europe, "West and South Africa, Cape Horn, and Australia. 



Fossil, included in Patella. 



Lepeta, Gray (p. 281). 



Derivation, possibly from Zepas, the ancient name ^ the 

 limpet. 



Type, Patella cseca, Miiller. 



Shell minute, apex posterior. Animal blind. 



Propilidium, Porbes and Hanley (p. 281). 



Derivation, from its affinity to the genus Pilidium. 



Type, P. ancyloide, Porbes. 



Shell similar to Lepeta, but differing in always having a dis- 

 tinctly spiral apex and a plate or septum inside the croT\Ti. 



Animal blind, as Tectura fulva and Lepeta ccsca of this family. 



' ' The tongue is very long, and the brown central spines con- 

 spicuous under the microscope resemble bramble-thorns in 

 miniature." — (Porbes and Hanley.) 



Distribution, 1 species. Shores of Ireland, Scotland, Sweden. 



Gadhstia (p. 281). 



Sub-genus : — Rowellia, Cooper. Animal with broad flat ten- 

 tacles, rounded and pectinated in front, projecting beyond the 

 shell ; foot moderate, round. Shell as in Oadinia. 



Pamilt 'KIN. — Dentaliad^. 

 Gadtjs, Eang, 1829. 



Synonym, Helonyx, Stimpson, 1865. 

 Example, Dentalium clavatum, Gould. 



Shell smnll, resembling that of Dentalium, contracted at the 

 anterior extremity, polished. 

 Animal with a greatly elongated cylindrical foot, obtuse at 

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