THE GASTROPODA 



165 



short, obtuse posteriorly ; shell thick with a short spire, the last whorl 

 large and the canal short ; aperture wide ; columella flattened ; operculum 

 horny. Genera Purpura, Bruguiere ; shell not umbilicated, aperture 

 smooth ; British. Rapana, Schumacher ; shell ventricose, umbilicated. 

 Monoceros, Lamarck ; shell like that of Purpura, but the aperture shifted 

 backward and bearing a conical tooth on its external border. Sistrum, 

 Montfort ; shell thick, spiny, the aperture contracted by the thickening 

 of the margins of the aperture. Concholepas, Lamarck ; shell ovoid, the 

 spire short and the aperture widely dilated. FAMILY 8. HALIIDAE, 

 Fischer. Foot large and thick ; without an operculum ; tentacles thick 

 and flattened ; shell ventricose, thin, and smooth, with a wide aperture. 

 Genus Halia, Risso ; from Cadiz and Morocco. FAMILY 9. CANCEL- 

 LARIIDAE, Adams. Snout short ; tentacles long, with the eyes at their 

 bases and external ; foot small ; no operculum ; siphon short ; shell 

 ovoid with short spire and folded columella. Genus Cancellaria, 

 Lamarck. FAMILY 10. COLUMBELLIDAE, Adams. Foot large, tentacles 

 long and convergent ; spire of shell prominent, aperture narrow, the 

 canal very short and the columella crenelated. 

 Genus Columbella, Lamarck. FAMILY 11. 

 CORALLIOPHILIDAE, Chenu. Foot short ; ten- 

 tacles slender and convergent ; siphon short ; 

 radula absent ; shell irregular ; sedentary 

 animals living in corals. Genera Corallio- 

 phila, Adams ; shell deformed, with a wide 

 aperture and a short canal ; operculum present. 

 Rhizochilm, Steenstrup ; no operculum ; the 

 aperture of the shell irregular, with the canal 

 prolonged into a tube. Leptocomhus, Riippel ; 

 no operculum ; the shell globular with a wide 

 aperture. Magilus, Montfort ; an operculum 

 present ; the last whorl of the shell uncoiled 

 and very thick. Rapa, Klein ; an operculum 

 present ; shell globular and umbilicated, the 

 aperture provided with a canal. FAMILY 12. 

 VOLUTIDAE, Gray. Head very flattened, and Fm 



transversally widened, with the eyes on the C onus liwatus, ventral aspect, 

 sides ; snout short ; foot broad ; siphon with T > or f, nce f the pedal gland ; n, 



_. - r r . T . mantle and opening of the palhal 



internal appendages. Genera Valuta, Lm- cavity ; ill, operculum ; iv, an- 



napii liparl with PVP Australian SPPS tenor glandular groove of the 



- as - foot ; V, eye and tentacle ; VI, 



Guivillea. Watson ; no eyes ; abyssal. Cymba, siphon ; vn, mouth. (After 



n i i o __!_ -ci Souleyet.) 



Brouerip and oowerby ; viviparous. TAMILY 



13. OLIVIDAE, d'Orbigny. Eyes, when present, on the middle of the 

 tentacles ; fore part of the foot with a transverse groove ; a posterior 

 pallial tentacle ; generally burrowing. Genera Oliva, Bruguiere ; eyes ; 

 no operculum. Olivella, Swainson ; tentacles without eyes ; an operculum. 

 Ancillaria, Lamarck. Agaronia, Gray. FAMILY 14. MARGINELLIDAE, 

 Adams. Foot very large ; mantle reflected over the shell. Genera 

 Marginella, Lamarck ; foot without operculum ; a central gland-pore. 

 Pseudomarginella, Carriere ; foot with an operculum and an anterior gland- 



