458 CALYPTR.ffiID.ffi. 



interrupted in the region of the head ; no internal par- 

 tition. 



Animal with a head produced into a proboseidiform 

 muzzle ; tentacula two, long, subulate, unconnected, with 

 the eyes or bulgings at their external bases ; mantle fringed 

 at the margin ; branchial plume single ; foot strong, sub- 

 orbicular, its sides plain. Tongue rather long with a 

 cordate membranous border at its anterior extremity ; 

 lingual teeth (according to Loven) arranged in transverse 

 series of seven, of which the central one is small and broad 

 with a hooked apex, and the others long and hamate. 



The shells of this genus are the most patelliform of their 

 tribe, and resemble little caps of liberty. The animal is 

 rather sluggish and sedentary, and sometimes secretes an 

 imperfect shelly disk from its foot ; hence it has been com- 

 pared with Hipponyx. The group is a very ancient one, 

 dating even to paleozoic times, and apparently extending 

 its range to the oldest fossiliferous rocks. Acroculia, of 

 Phillips, founded for some of these ancient forms of 

 Pileopsis, scarcely differs generically. We have preferred 

 using the name given by Lamarck to that of Oapulus 

 given by De Montfort, under the conviction that priority 

 alone cannot be admitted as sufficient ground for the adop- 

 tion of a generic appellation in Malacology, since in that 

 case appellations given by ignorant dealers or authors, 

 who, like Perry, did not even pretend to science, or such 

 random and worthless empirics as De Montfort was, will 

 have too often to be preferred before the nomenclature 

 resulting from earnest and scientific study. Specific appel- 

 lations had best be as often as possible determined by right 

 of priority, since though the original description or figure 

 might be bad, there was still the recognition of a distinct 

 object on the part of the founder; but the establishment of 



