GASTEEOPODA. ^'^'^ 



Shell, hyaline, globular or subulate, apex tapering, styliform, nucleus 



sinistral. 



Animal with slender, cyUndrical tentacles, and small sessile eyes at then 

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

 lai-ge, with a frontal lobe. Branchial plume single. Attached to the spines 

 of sea-ui'chins, or immersed in living star fishes and corals. 



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



LoxoNEMA, Phillips. 

 Eti/m., loxos, obUque, and nema, thread ; in aUusion to the striated sur- 

 face of many species. 



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

 below, with a sigmoidal edge to the outer lip. 



lossil, 75 sp. L. silm-ian— 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 caUous, slightly tortuous. 

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

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



PAMILY III. Cerithiad^. Cerites. 

 Shell spiral, elongated, many-whii'led, frequently varicose ; aperture chan- 

 nelled in front, with a less distinct posterior canal; lip generaUy 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., 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, paucispfral. PI. VIII., fig. 16=". 



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

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



Fossil. 460 sp. Trias—. Brit., France, U. States, &c. 



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

 operc, sub-spiral. 



Bittiimi, Leach. C. reticulatum, PI. VIII., fig. 17. SmaU northern 

 species, ranging from low-water to 80 fathoms. 



