GASTEROPODA. 275 
tentacles; it is found in shallow water, and walks freelry. 
(Cuming. ) 
Distribution, 15 species. New Zealand, Australia, Philippines, 
Singapore, Red Sea, Cape. 
. Fossil, 8 species. Hocene?—. Paris Basin. 
FAMILY XIJ.—CALYPTRHIDH. 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 
ZC 
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. lLovén places this family next to the Velutinide. 
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 calyptrea, 
which Professor Forbes kept in a glass, ate a small sea slug 
(goniodoris) which was confined with it. Both calyptrea and 
ptleopsis sometimes coyer and hatch their spawn in front of their 
foot. (Alder and Clarke.) 
_ Dr. Gray arranges the bonnet-limpets next after the yerme- 
tides ; their lingual dentition is like velutina. 
