GASTEROPODA. 275 



tentacles; it is found in shallow water, and walks freely. 

 (Cuming.) 



Distribution, 15 species. New Zealand, Australia, Pliilippines, 

 Singapore, Eed Sea, Cape. 



Fossil, 3 species. Eocene ? — . Paris Basin. 



Family XII. — Calyptr^id^. Bonnet-limpet. 



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

 simple, or divided by a shelly process, variously shaped, to 

 which the adductor muscles are attached. 



Animal with a distinct head ; muzzle lengthened ; eyes on the 

 external bases of the tentacles ; branchial plume single. Lin- 

 gual teeth single, uncini 3, as in Fig. 119, which shows dentition. 



Fig. 119. Crepidula. (Wilton.) 



of crepidula. The rostrum is prominent and split, but non- 

 retractile ; the median tooth hooked and dentate ; the first, or 

 first and second laterals serrated, the third claw- shaped and 

 simple. Loven places this family next to the Velutiniclee. 



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 

 surface beneath, whilst some wear away the space beneath their 

 foot, and others secrete a shelly base. Both their form and 

 colour depend on the situation in which they grow ; those found 

 in the cavities of dead shells are nearly flat, or even concave 

 above, and colourless. They are presumed to feed on the sea- 

 weed growing round^ them, or on animalcules ; a calyptrcaa, 

 which Professor Forbes kept in a glass, ate a small sea slug 

 [goniodoris) which was confined with it. Both calyptrcea and 

 pileopsis somertimes cover and hatch their spawn in front of their 

 foot. (Alder and Clarke.) 



Dr. Gray arranges the bonnet-limpets next after the verme- 

 tidae ; their lingual dentition is like velutina. 



