GASTEROPODA. 151 



Sub-gemis. Hemitonia, Sw. Type, E. octoradiata. (E. rugosa. PL XL, 

 figs. 7, 8.) Shell depressed ;. anterior margin slightly channelled. 



Parmophorus, Blainville. Duck's-bill limpet. 



Eti/m., 2^arme, a shield, ?a\^ phoreus, a bearer. 



Ti/i^e, P. australis. PL XL, fig. 9. Syn., Scutus, Montf. 



Shell leugthened-oblong, depressed ; apex posterior ; front margin arched. 

 Muscular impression horse-shoe shaped, elongated. The shell is smooth and 

 white, and permanently covered by the reflected borders of the mantle. The 

 animal is black, and very large compared with the shell ; its sides are fringed 

 with short cirri, and its eyes sessile on the outer bases of thick tentacles ; it 

 is found in shallow- water, and walks freely (Cuming). 



Distr., 10 sp. New Zealand, Australia, PhiKppines, Singapore, Red Sea, 

 Cape. 



Fossil, 3 sp. Eocene ? — . Paris basin. 



FAMILY XII. CALYPTRiEiDiE. Bonnct-limpets. 



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

 -divided by a sheUy-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. Lingual teeth single, uncini 3. 



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 smface 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 colour- 

 less. They are presumed to feed on the sea-weed growing round them, or on 

 animacules ; a calyptrc^a, which Professor Foi'bes kept in a glass, ate a smaR 

 sea slug {goniodoris) which was confined with it. Both calyptraa and |J27^- 

 opsis sometimes cover and hatch their spawn in fi'ont of their foot (Alder and 

 Clarke) . 



jMr. Gray arranges the bonnet-limpets next after the vermetidse ; their 

 lingual dentition is like velidina. 



Calyptr.tEA, Lam. Cup-and-saucer limpet. « 



Eti/m., calyptm, a (lady's) cap. 



Syn., lithcdaphus, Owen. 



Types, C. equestris. PL XI., fig. 10. C. DiUwynnii, fig. 11. 



Shell conical ; limpet-shaped ; apex posterior, with a minute, spiral 

 nucleus , margin in'cgular ; interior with a half-cup shaped process on the 

 posterior side, attached to the apex, and open in front. Surface rugose or 

 cancellated. 



