OF MOLLUSCA. 119 



ft Internal cup large, nearly sessile, on the side of the cavity of 

 the shell. 



2. C. lignarium, t. 130. f. 2 ; Adams, Gen. Moll. t. 40. f. 4. 



The Crucibula, like the Crepidulee, are often grouped together, 

 forming large masses, and one shell attached to the hack of the other. 

 They also assume the character of the surface of the shell to which 

 they are attached ; those on Pectens, &c. being rayed. 



In all the varieties of Crucibulum rugosum the foot is circular, 

 becoming thicker as the shell is higher, yellowish above, spotted 

 with black on the sides ; the cephalic mass oblong, transverse, 

 distinct. Tentacles elongate, acute, with the eyes in their middle. 

 The buccal appendices separated into two very blunt, as if truncated 

 lobes. 



The place where the animal of Crucibulum imbricatum is fixed is 

 often a little eroded. 



The body of Crucibulum lignarium has a small roundish form, and 

 is only slightly larger than the cup-like internal cavity of the shell ; 

 the rest of the cavity of the shell within the mantle being occupied 

 with the large head of the animal, which is oblong, transverse, and 

 rounded on the sides behind the subulate tentacles, which have the 

 eyes placed on their outer side rather above the base, and the fore- 

 head is divided into two truncated rounded lobes. 



c. Calyptraina. Foot forming a shelly inferior plate. Shell conic, 

 with a folded process under the apex. 



6. Calyptra. 



1. C. equestris, Owen, Trans. Zool. Soc. ; Adams, Gen. Moll. t. 40. 

 f. 3 (shell and base). 



Fam. XXI. CAPULID^E. 



Shell conical, cup-shaped. Apex subspiral, small. Posterior 

 cavity simple. The front of the body scarcely produced. The 

 rostrum elongate, depressed, annulated. Lips produced into a long, 

 hamate canal. Tentacles elongate, subulate, at the base of the 

 rostrum, united by a short band continued over the base. Gill com- 

 posed of elongated, slender filaments. Foot folded on itself, and 

 often secreting a shelly plate or forming a cavity in the body to 

 which it is attached. Egg-cases membranaceous, attached in a tuft 

 on the front of the foot. 



* Foot simple or secreting a shelly plate. 



1. Capulus. 

 The foot naked, without any under shell. 

 1. C. ungaricus, t. 268. f. 12 ; Forbes §■ Hanley, B. M. t. C.C. f. 5. 



