236 MANUAL OF THE MOLLUSCA. 



Operculum, horny. 



Neverita, Bisso. N. Alderi. Eig. 95. 



Lunatia, Gray. N. Ampullaria. Perforation simple ; epider- 

 mis dull, olivaceous. Northern seas. 



Globulus, J. Sby. (Ampulina, Deshayesnot Bl.) N. Sigaretina. 

 PI. YIII., Pig. 2. Umbilicus narrow (rimate), lined by a thin 

 callus. 



Fossil, Eocene. Britain, Paris. 



Folinices, Montfort (naticella, Guild.), N. mammilla. Shell 

 oblong ; callus very large, filling the umbilicus. 



Cernina, Gray, N. fluctuata. PL YIII., Pig. 3. Globular, 

 imperforate ; inner lip callous, covering part of the body-whorl. 



Naticella, Miiller. 19 species. 



Fossil, Trias, S. Cassian. 



Deshayesia, Eaulin 



Miocene, Prance. Some additional species have been found 

 with a similar oblique aperture and corrugated inner lip. 

 Baron Eyckholt has described a species {D. Raulini), from the 

 Devonian, Belgium. The relation of the genus is uncertain. 



Naticella, Miinster. 



This genus, abounding in the Trias of St. Cassian, has been 

 referred to Natica by D'Orbigny. A characteristic species 

 occurs in the green-sand of Blackdown, and has been named 

 Natica carinata, J. Sby. (Narica, D'Orbigny.) It is exactly 

 intermediate between Narica (p. 23*7) and Fossarus (p. 253), and 

 appears to form with them a little group nearly related to 

 Lacuna (p. 255). 



SiGAEETirs (Adans.), Lamarck. 



Synonyms, Cryptostoma, Bl. Stomatia, Browne. 



Type, S. haliotoides. PL YIII., Pig. 4. 



Shell striated ; ear-shaped ; spire minute : aperture very wide, 

 oblique (not pearly) ; operculum minute, horny, sub-spiral. 



The flat species are entirely concealed by the mantle when 

 living ; the convex shells only partially, and they have a 

 yellowish epidermis. The anterior foot lobe {mentum) is enor- 

 mously developed. 



Distrihution, 31 species. West Indies, India, China, Peru. 



Fossil, 10 species. Eocene — . Britain, Prance, South America. 



Sub-genus. Naticina, Gray. N. papilla, PL YIII., Pig. 3. 

 Shell ventricose, thin, perforated. West Indies, Eed Sea, China, 

 North Australia, Tasmania. Eocene, Paris. 



