MANUAL OF THE MOLLUSCA. 
apex of embryonic shell slightly 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 asin Patella, and forming a shorter plume, which is 
interrupted over the head. 
Helcion lives on Laminarie 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 lepas, the ancient name of the 
limpet. ; 
Type, Patella ceeca, Miller. 
Shell minute, apex posterior. Animal blind. 
PROPILIDIUM, Forbes and Hanley (p. 281). 
Derivation, from its affinity to the genus Pilidium. 
Type, P. ancyloide, Forbes. 
Shell similar to Lepeta, but differing in always haying a dis- 
tinctly spiral apex and a plate or septum inside the crown. 
Animal blind, as Tectura fulva and Lepeta ceca of this family. 
«‘ The tongue is very long, and the brown central spines con- 
spicuous under the microscope resemble bramble-thorns in 
miniature.”—(Forbes and Hanley.) - 
Distribution, 1 species. Shores of Ireland, Scotland, Sweden. 
GADINIA (p. 281). 
Sub-genus :—-Rowwellia, Cooper. Animal with broad flat ten- 
tacles, rounded and pectinated in front, projecting beyond the 
shell; foot moderate, round. Shell asin Gadinia. 
Famity XIV.—DENTALIADZ. 
GADUS, Rang, 1829. 
Synonym, Helonyx, Stimpson, 1865. 
Example, Dentalum clavatum, Gould. 
Shell small, resembling that of Dentaliwm, contracted at the 
anterior extremity, polished. 
Animal with a greatly elongated cylindrical foot, obtuse at 
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