GASTEROPODA. 331 



tentacular processes ; gills with. 2 or more lateral appendages. 

 (A. and H.) 



Bistribution, Norway (8 species), Britain, Eed Sea. Within 

 tide-marks and in deep water on corallines. The spawn is strap- 

 shaped, and coiled on stones, in July and August. P. ocellata 

 {Plocamophorus, Eiippell) has the cephalic tentacles branched. 



Idalia, Leuckart. 



Etymology, Idalia, Yenus, from Mount Idalium, in Cyprus. 



Synonyms, Euplocamus, Phil. Peplidium (Maderse), Lowe. 



Example, I. aspersa, PI. 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 very small, margined with filaments ; lingual 

 teeth 2.0.2. 



Distribution, 14 species. Norway, Britain (4 species), Medi- 

 terranean, Madeira, Japan. 



Ancula, Loven. 



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 veil j)roduced 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. 



inimal oblong, narrow, with two large and prominent hom- 



3 processes on the posterior j)art of the back, behind the gills; 



s 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. 

 Brancbise in a circular disk on the back, non-retractile. 



Distribution, X species (T, Ceylonica). Ceylon, 



