TURRITELLID^E. 



About a hundred species are known, inhabiting all seas, but 

 principally tropical and subtropical. The fossils number about 

 four hundred species ; the genus commenced in the trias. 



The genus Proto, Defrance, 1824, is probaj% founded on a 

 young Turritella : Proto of authors (Protoma, Baird) is different. 



Section I. TURRITELLA (restricted). 



Whorls rounded, spiral!} 7 striate, unicolored, aperture rounded. 

 Section II. HAUSTATOR, Montfort, 1810. 



Whorls flattened, mouth subquadrangular, outer lip sinuous ; 

 usually undulatingly strigate with chestnut-color. 



Section III. TORCULA, Gray, 1847. 



Shell turriculated, usually white or horn-colored with faint 

 strigations of chestnut-color ; whorls subangular, with a median 

 excavation ; aperture subquadrangular, the outer lip with a slight 

 median sinus. 



Section IY. ZARTA, Gray, 1841. 



Shell turriculated, without color markings ; whorls carinated ; 

 aperture subquadrangular, outer lip simple. 



Section Y. TURRITELLOPSIS, Sars, 1878. 



Shell like Turritella, the whorls of the spire grooved across ; 

 aperture oval. The radula is without marginal teeth. Inhabits 

 boreal seas. Tachyrhynchus, Morch., 1868, separated from 

 Mesalia by a slight difference in the operculum, is a synonym. 

 I do not adopt it instead of Turritellopsis because the real dif- 

 ferences of radula, size and habitat are not mentioned. 



Subgenus MESALIA, Gray, 1842. 



Shell turritelliform, the last whorl rounded; aperture oval, 

 slightly produced in front into a rudimentary channel, lip sharp, 

 arcuated, slightly sinuous behind, columella flattened, a little 

 twisted at the base. Operculum with fewer whorls than in Tur- 

 ritella, the nucleus central. Lateral and marginal teeth of the 

 radula with smooth edges. 



West Africa ; fossil in the Eocene. 

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