GASTEROPODA. 331 
tentacular processes; gills with 2 or more lateral appendages. 
(A. and H.) 
Distribution, Norway (8 species), Britain, Red Sea. Within 
tide-marks and in deep water on corallines. The spawnisstrap- 
shaped, and coiled on stones, in July and August. P. ocellata 
(Plocamophorus, Riippell) has the cephalic tentacles branched. 
IpALtIA, Leuckart. 
Etymology, Idalia, Venus, from Mount Idalium, in Cyprus. 
Synonyms, Euplocamus, Phil. Pepldium (Maderz), Lowe. 
Example, I. aspersa, Pl. XIII., Fig. 6. Coralline zone. 
Animal broadly oblong, nearly smooth, tentacles clavate or 
linear, with filaments at their base; head slightly lobed at the 
sides; mantle yery small, margined with filaments; lingual 
teeth 2.0.2. 
Distribution, 14 species. Norway, Britain (4 species), Medi- 
terranean, Madeira, Japan. 
ANCULA, Lovén. 
Synonym, Miranda, A. and H. 
Type, A. cristata, Alder. 
Animal slender, elongated; mantle entirely adnate, orna- 
mented with simple filaments; tentacles clavate, laminated ; 
with filiform appendages at their base; labial yeil produced on 
each side. 
Distribution, 2 species. Norway and Britain. Length, 4 inch. 
CERATOSOMA. (Gray), A. Adams. 
Etymology, ceratois, horned, soma, body. 
Type, C. cornigerum, Ad. 
Animal oblong, narrow, with two large and prominent horn- 
like processes on the posterior part of the back, behind the gills; 
gills 5, bipinnate; dorsal tentacles clavate, laminated, rising 
from rounded tubercles, non-retractile ; head with short lateral 
processes ; foot narrow. 
Distribution, 2 species. Sooloo Sea. (A. Adams.) 
TREVELYANA, Kelaart. 1858. 
Body without a cloak. Two dorsal tentacles, without sheaths ; 
non-retractile. Mouth in front of head, without tentacles. 
Branchice in a circular disk on the back, non-retractile. 
Distribution, 1 species (T. Ceylonica). Ceylon. 
