

GASTEROPODA. 127 



Shelly hyaline, globular or subulate, apex tapering, styliforra, nucleus 

 sinistral. 



Animal with slender, cylindrical tentacles, and small sessile eyes at theii 

 outer bases ; mantle thick, reflected over the last whirls of the shell ; foot 

 large, with a frontal lobe. Branchial plume single. Attached to the spines 

 of sea-urchins, or immersed in living star fishes and corals. 



PDistr., 6 sp. W. Indies, Brit., Philippines, Gallapagos. 

 . 



LOXONEMA, Phillips. 



Etym.y loxos, oblique, and nema, thread ; in allusion to the striated sur- 

 face of many species. 



Shell elongated, many-whirled ; aperture simple, attenuated above, effused 

 below, with a sigmoidal edge to the outer lip. 



Fossil, 75 sp. L. siluriaii Trias. N. America, Europe. 



MACROCHEILUS, Phillips. 

 Etym., macros, long, and cheilos, lip. 



Shell, thick, ventricose, buccinoid ; aperture simple, effuse below ; outer 

 lip thin, inner lip wanting, columella callous, slightly tortuous. 

 Type, M. arculatus, Schlotheim sp. Devonian. Eifel. 

 Fossil, 12 sp. Devonian Carboniferous. Brit., Belgium. 



FAMILY III. CERITHIADJS. Cerites. 



Shell spiral, elongated, many-whirled, frequently varicose ; aperture chan- 

 nelled in front, with a less distinct posterior canal ; lip generally expanded 

 in the adult ; operculum horny and spiral. 



Animal with a short muzzle, not retractile ; tentacles distant, slender ; 

 eyes on short pedicels, connate with the tentacles ; mantle-margin with a 

 rudimentary siphonal fold ; tongue armed with a single series of median 

 teeth, and three laterals or uncini ; marine, estuary, or fresh-water. 



CERITHIUM (Adans.). Bruguiere. 



Etym.y ceration, a small horn. 



Type., C. nodulosum. PI. VIII., fig. 16. 



Shell turreted, many-whirled, with indistinct varices; aperture small, 

 with a tortuous canal in front; outer lip expanded; inner lip thickened. 

 Operculum horny, paucispiral. PI. VIII., fig. 16*. 



Distr., above 100 sp. World-wide, the typical species tropical Norway, 

 Brit., Medit., W. Indies, India, Australia, China, Pacific, Gallapagos. 



Fossil. 460 sp. Trias. Brit., Trance, U. States, &c. 



Sub-genera. Rhinoclavis, Sw. C. vertagus. Canal long, bent abruptly 

 operc., sub- spiral. 



Bittium, Leach. C. reticulatum, PI. VIII., fig. 17. Small northern 

 species, ranging from low-water to 80 fathoms. 



