464 PATELLIDiE. 



inner surface of the mantle, forming a more or less com- 

 plete ring just beneath the margin. Side of foot with a 

 sunken groove. 



Operculum none. 



Shell simple, conical; muscular impression crescentic, 

 interrupted in front. 



The continuous series of branchial lamellae forming a 

 fixed cordon between the mantle and foot, together with 

 the peculiarities of their lingual dentition, serve to distin- 

 guish this family from the Tecturidcs ; from the Chito- 

 nid(B the presence of tentacles and eyes, and the simple, 

 conical nature of the shell at once separate them. The 

 PatellidcB are strictly littoral in their habits, living upon 

 the rocks between tide-marks; they are chiefly sedentary, 

 adhering firmly by atmospheric pressure, and feeding on 

 the sea-weed within reach of their long tongues ; during 

 the night-time, however, they make short excursions, in- 

 dicated by the irregular tracks they form, probably by 

 rasping the surface of the rocks with their foot. 



Genus PATELLA, Linnseus. 



Mouth emarginate below ; gills extending nearly round 

 the body, interrupted on one side near the neck. 



Shell non-spiral, orbicular or oval, depressly-conical, 

 surface smooth, or with radiating ribs or striae ; apex sub- 

 central, inclined anteriorly ; aperture wide, the margin 

 entire or spinose, simple within. 



Syn. YaieWdiXiQ.y Llwyd. ^vucsl, Tournef., not Swains. 

 Patellus, Montf. Patellarius, Dum. Goniclis, Rafin. 



Ex. P. vulgata, Linnaus, pi. 52, fig. 9. Shell, P. tes- 

 tudinaria, Linn., fig. 9, a. 



