GASTEROPODA. 151 



Sich-gemis. Hemitoma, S\v. Type, E. octoradiata. (E. rupiosa. PL XL, 

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



Parmophorus, Blainville. Duck's-bill limpet. 



Etijm., parme., a shield, ^wdijjJioreus, a bearer. 



Ti/pe, P. australis. PI. XL, fig. 9. Syn., Scutus, Montf. 



Shell lengthened-oblong, depressed ; apex posterior ; front margin arehed. 

 ^^useiilar 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 fi'inged 

 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, Philippines, Singapore, Eed Sea, 

 Cape. 



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



FAMILY XII. Calyptr.eid.e. Botmet-limpcts. 



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

 di\dded by a shelly-process, vai'iously shaped, to wliich the adductor muscles 

 are attached. 



Ammal with a distinct head ; muzzle lengthened ; eyes on the external 

 ba^es of the tentacles ; branchial plume single. Lingual teeth single, miciui 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 sm-face beneath, whilst some wear away 

 tlie space beneath their foot, and others secrete a sheUy 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 colom-- 

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

 animacules ; a cahjidr<za, which Professor Forbes kept in a glass, ate a small 

 sea slug {g 07110 dor is) which was confined with it. Both cahjptreea and pile- 

 opsis sometimes cover and hatch their spawn in front of their foot (Alder and 

 Clarke). 



Mr. Gray arranges the bonnet-limpets next after the vermctida.' ; their 

 lingual dentition is like velutiua. 



Calyptr.ea, Lam. Cup-and-saucer limpet. 



Ett/rn., cahjptra, a (lady's) cap. 



Syn., lithedaphus, Owen. 



Types, C. equestris. PI. XL, fig. 10. C. Dillwynnii, fig. 11. 



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

 nucleus ; margin iiTcgular ; interior with a half-cup shaped process on the 

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

 cancellated. 



