366 MOLLUSC A. 



culum; the animal is like a true Nerita, and most generally the 

 columella is not dentated. It inhabits fresh water. 



A small species, very prettily coloured, abounds in the rivers 



of France; it is the Nerita fluviatilis, L. ; Chemn., IX, cxxiv, 



188(1). 



The columella in others, however, is finely crenulated(2), and of 



this number there are some in which the spire is armed with long 



spines Clithon, Mont. (3) 



FAMILY II. 



CAPUL0IDA(4). 



Recent researches liave convinced us that it is to the Tro- 

 choida that we must approximate this family, which contains 

 five genera, four of which are taken from the Patellse.. They 

 all have a widely opened, scarcely turbinated shell, with nei- 

 ther operculum, emargination nor siphon; the animal resem- 

 bles the other Pectinibranchiata and has the sexes separate. 

 There is but one branchial comb transversely arranged on the 

 roof of the cavity, and its filaments are frequently very long. 



Capulus, Montf. Pileopsis, Lam. 



A conical shell with a recurved and spiral summit, which has long 

 caused it to be placed among the Patellse; the branchiae are in one 

 range under the anterior margin of the branchial cavity; the pro- 

 boscis is long, and there is a closely plaited membranous veil under 

 the neck; the eyes are at the external base of the conical tenta- 

 cula(5). The 



HiPPONYx, Defr. 



Would appear from the shell to be a fossil Capulus, very remark- 



(1) Add, Nerifa turrita, Chemn., IX, cxxiv, 1085. 



(2) Nerita puUigcra, Chemn., loc. cit., 1878 1879; iV. virginea, List, 604, 

 606. 



(3) Nerita corona, Chemn., 1083, 1084. 



(4) M. deBlainville places most of them among' his hermaphroditical, nonsym- 

 metrical Paracephalophm-a; but they all appear to me to be dixcious. 



(5) Patella hungarica, List., 544 32; Pa/, calyptra, Chemn., X, clxix, 1643 

 44; Pat. mitrula, Gm., List., dxliv, 31. 



