FAMILY CALYPTRMIDM. 



Shell limpet-like, with a more or less spiral apex, interior 

 simple or parti}- occupied by a shelly process, variously shaped, 

 to which the adductor muscles are attached. 



Animal with a distinct head and lengthened muzzle ; eyes near 

 the external base of the tentacles ; only one branchial plume is 

 developed. 



The bonnet-limpets are found adhering to stones and shells ; 

 most of them appear never to quit the spot on which they first 

 settle, as the margins of their shells become adapted to the 

 irregularities of the surface beneath, whilst some wear away the 

 space beneath their foot, and others secrete a shelly base. The 

 form and color of the shell both depend somewhat upon the situ- 

 ation in which it grows ; those found on the inside of the mouth 

 of dead shells are generally flat or even concave above and 

 white ; those attached to the outside of shells are convex and 

 colored. The animal is supposed to feed on sea-weed and ani- 

 malcules ; and an individual kept alive in a glass by Professor 

 Forbes, ate a small nudibranch (Goniodoris),its fellow prisoner. 

 Both Calyptraea and Pileopsis sometimes cover and hatch their 

 spawn under the forepart of the foot. The inner process or shelf 

 of the shell forms a support for the viscera. The branchia of 

 this family is composed of narrow, rigid filaments, and Gray has 

 created for this type the division Plocamobranchia. 



Subfamily Calyptrseinse. 



Muzzle slit at its extremity ; tentacles subulate, carrying eyes 

 near their base ; foot short, rounded oval ; the single branchia 

 finely and deeply pectinated ; adductor muscle horse-shoe shaped 

 or oval ; jaws rudimentary ; radula with a subquadrangular 

 middle tooth, the margin pectinated, the central cusp longer; 

 lateral teeth with denticulate margins ; marginals narrow, curved, 

 denticulate (plain in Capulus). 



Shell conic, patelliform, the summit more or less spiral; 



(101) 



