314 MANUAl OF THE MOLLUSC A. 



twisted, and directed slightly outwards. (B.) Shell oval, spire 

 sunk, whorls with acute margins. Bath Oolite, Britain. 



Acteonina, D'Orbigny. Tornatellse "without columella 

 plaits," 30 species. Garb. — Portlandian (including Cylindrites). 



Adeonella, D'Orbigny. A. Eenauxiana, PI. XIV., Fig. 3. 

 Shell thick, cone-like or conyoluted, spire short or concealed, 

 aperture long and narrow, columella with 3 strong and regular 

 spiral plaits in front. Distribution, 18 species. Chalk ; Britain, 

 Trance. 



Adeon Oahanetiana, D'Orbigny. {Itieria, Matheron, 1842), 

 Coral-rag, Erance, belongs to the genus Nerincea (D'Orbigny), 

 p. 244. 



CiTiTcrLLA., Gray. 



Type, C. ayellana, PL XIY., Pig. 4. 



Synonyms, Avellana and Einginella, D'Orbigny. 



Shell globular, thick, spirally grooved and punctate, spire 

 small ; aperture narrow, rounded and sinuated in front ; outer 

 lip thickened and reflected ; crenulated inside, columella with 

 several tooth-like folds. 



Fossil, 21 species. Neocomian — Chalk. Britain, Prance. 



EiNGiCTJLA, V. p. 222, PL y.. Pig. 21. 

 Globiconcha, D'Orbigny. 

 Type, G-. rotundata, D'Orbigny. 

 Fossil, 6 species. Chalk. Prance. 



Shell ventricose, smooth, aperture crescent-shaped, simple, 

 not toothed or thickened on the columellar side. 



Yahigera, D'Orbigny. 1850.* 



Type, V. Guerangi, D'Orbigny. 



Fossil, 8 species. Neoc : — . Chalk. Prance. 



Shell like Glohiconcha, but with lateral varices. 



Tylostoma, Sharp. 1849. 



Type, T. Torrubise, Sharp. 



Etymology, Tulos, a callosity, stoma, mouth. 



Shell ventricose, smooth or punctate-striate, spire moderate, 

 aperture ovate-lunate, pointed above, rounded in front ; outer 

 lip periodically (once or twice in a whorl) thickened inside and 

 expanded, rising slightly ; inner lip callous, spread over body- 

 whorl. 



Distribution, 4 species. L. Cretaceous rocks, Portugal. 



* The dates of M. D'Orbigny's genera, given in the Prodrome de Paleontologies are 

 dates of invention; the names were not published, in many instances, until ytdrs 

 alterwards. 



