GASTEROPODA. 319 
oblong; eyeless; foot broad; lateral lobes large, but not 
enveloping; tongue with two or four series of sickle-shaped 
uncim ; gizzard with three longitudinal shelly plates. Egg 
Fig. 138. Philine aperta.* 
capsules ovate, in single series on a long spiral thread; fry 
with a ciliated head-veil and an operculated, spiral shell. 
(Lovyén.) 
Distribution, 16 species. West Indies, Greenland, Norway, 
Britain, Mediterranean, Corea, Borneo. 
Fossil, 7 species. Hocene—. France. 
Sub-genus. Chelidonura, A. Adams, (Hirundella, Gray) B. 
hirundinaria, Quoy, Mauritius. Shell concealed; outer lip 
produced posteriorly into a spur; columellar:border inflected. 
Animal with enveloping side-lobes ; mantle with two appendages 
behind, like the lateral processes of Hyalaea. 
Doripium, Meckel. 
Etymology, diminutive of Doris. 
Synonym, Acera, Cuyier. Hidothea, Risso. 
Type, D. membranaceum, Meck. Mediterranean. 
Distribution, 3 species. South Europe. 
Animal oblong, truncated behind, the angles produced and 
dilated or filiform; head oyate-oblong, retuse in front; side- 
lobes expanded, wing-like; mantle investing a rudimentary, 
membranous shell. 
GASTROPTERON, Meckel. 
Type, G. Meckelii, Bl. (Clo amate, Chiaje) Mediterranean. 
Animal shell-less, oval, with side-lobes developed into wing- 
like expansions, meeting and uniting behind; cephalic disk 
triangular, obtuse in front, pointed behind, eyes centrally 
immersed; lingual teeth 5.1.5; mantle? branchial plume 
exposed on the right side; reproductive orifice in front of the 
* From a specimen dredged at Folkestone ; 0, mouth; c, head, or cephalic disc, 
t, side-lobes of the foot; m, mantle. The shells, and gizzard g, are indistinctly seen 
through the translucent integuments. ; 
