332 PATELLID^. 



scuTELLiNA, Gray. Shell with a broad margin internally. 7 

 sp. Red Sea, Philippines, Pacific, Panama. A. crenulata, Urod. 



Pectinodonta, Dall. 



Distr. — P. arcuata, Dall. West Indies. 



Shell resembling Acmsea, with a blunt subcentral apex. 



Animal blind, with the front part of the head between the 

 tentacles and above the muzzle much produced upward and 

 forward, extending considerably further forward than the end of 

 the muzzle. Muzzle marginated, with lappets at the outer 

 corners. Jaw thin, translucent. Gill exactly as in A cm sea ; 

 sides of foot and mantle-edge simple, nearly smooth. 



LoTTiA, Gray. 



Syn. — Tecturella and Tecturina, Carp. 



Distr. — L. gigantea^ Sowb. (Ixxxiii, 22). West Coast of N. 

 America. 



Shell patelliform, depressed, the apex anterior. 



Animal with a single cervical branchia, but also furnished 

 with a branchial cordon of laminae between the mantle-edge and 

 the foot, extending as far forward as the adductor muscle on 

 each side and continuous behind ; frill of the muzzle without 

 lappets. The typical and only species is among the largest and 

 most active of limpets, the shell attaining three inches in length. 



ScuRRiA, Gray. 



Distr. — Several sp. West Coast of North and South America. 

 S. scurra, Lesson (Ixxxiv, 48;. 



Shell patelliform, conical, elevated, rather thick and of rude 

 growth. Branchiae completely surrounding the bodj'', as in 

 Patella, but having also the cervical plume of Acmsea ; muzzle 

 without lappets. 



scuRRiOPSis. Gemmellaro. Shell with radiating riblets crossed 

 by concentric gi'owth-lines. Jurassic. 



Subfamily PATELLINJE. 



Shell conical, with the apex turned forward ; muscular impres- 

 sion horseshoe-shaped, open in front, as in the preceding groups. 



Animal. Gills forming a roAv of leaflets surrounding the body ; 

 no cervical plume-like gill ; radula provided with three lateral 

 teeth on each side, and three uncini ; rachidian tooth rarely 

 present (xii, 51 ). 



The continuous series of branchial lamellae forming a fixed 

 cordon between the mantle and foot, together with peculiarities 

 of their lingual dentition, serve to distinguish this subfamily 

 from the preceding one. These animals are strictly littoral in 

 habit, living upon the rocks between tide-marks ; they are 

 chiefly sedentary, adhering firmly by atmospheric pressure, and 



