250 MAJftl-LL OF THE MOLLt/SCA, 



ScAiiABiA, Lam. Wentle-trap. 



Etymology, scalaris, like a ladder. 



Type, S» pretiosa, PL IX., Fig. 9. (=== T. scalaris, L.) 



Shell mostly pure wliite and lustrous ; turreted ; many- 

 whorled; whorls round, sometimes separate, ornamented with 

 numerous transverse ribs ; aperture round ; j)6i'istome con- 

 tinuous; operculum horny, few-whorled. 



Animal with a retractile proboscis-like mouth ; tentacles 

 close together, long and i^ointed, with the eyes near their outer 

 bases ; mantle-margin simple, with a rudimentary siphonal 

 fold ; foot obtusely triangular, with a fold (mentum) in front. 

 Lingual dentition nearly as in huUa ; teeth ; uncini nume- 

 rous, simple ; sexes distinct ; predacious ? Eange from low 

 Water to 80 fathoms. The animal exudes a purple fluid when 

 molested. 



Distrihution, 104 species. Mostly tropical. Greenland, 

 Norway, Britain, Mediterranean, West Indies, China, Australia, 

 Pacific, "West America. 



Fossil, nearly 100 species. Coral-rag — . Britain, North 

 Am.erica, Chili, India. 



Family YI. — ^LiTTORmro^. 



Shell spiral, turbinated or depressed, never pearly ; aperture 

 rounded ; peristome entire ; operculum horny, pauci- spiral. 



Animal with a muzzle-shaped head, and eyes sessile at the 

 outer bases of the tentacles ; tongue long, armed with a median 

 series of broad, hooked teeth, and 3 oblong, hooked uncini. 

 Branchial plume single. Foot with a linear duplication in 

 front, and a groove along the sole. Mantle with a rudimentary 

 siphonal canal ; operculum lobe appendaged. 



The species inhabit the sea, or brackish water, and are mostly 

 littoral, feeding on algae. 



LiTTomisrA, Ferussac. Periwinkle, 



Etymology, littoralis, .belonging to the sea-shore. 

 Type, L. littorea, PI. IX., Pig. 10. 

 Bhdl turbinated, thick, pointed, few-whorled; 

 aperture rounded, outer li23 acute, columella rather 

 flattened, imperforate, operculum pauci-spiral, Pig. 

 103. Lingual teeth hooked and trilobed ; uncini 

 Fig 103. hooked and dentated (Pig. 104). 

 Distrihution, 131 species. The periwinkles are found on the 

 Rca--hore in all parts of the world. In the Baltic they live 



