MANUAL OF THE MOLLUSCA. 



Scalenostoma, Deshayes, 1863. 



Type, S. carinatum, Isle of Bourbon. 



Shell in form allied to Pyramidetta and Niso, tirrriculated T 

 white, imperforate ; columella not plicated ; opening subtri- 

 angular, slightly bent in the direction of its length ; margin 

 simple, notched near the suture. 



Cheienitzia. Sub-genera : — Dunheria, P. Carpenter (dedi- 

 cated to Professor "W. Dunker). Aperture as in Chemnitzia, 

 but the whorls rounded as in Aclis ; whorls cancellated. 



Distribution, 7 species. Mazatlan, Japan. 



Pseudomelania, Pictet and Campiche, 1864. 



Etymology, pseudo, false, and Melania, a generic name. 



Shell turriculated, spire acute, test thick, imperforate, 

 without ornamentation. Aperture oval, rounded in front, more 

 or less angulated behind ; columella thick, conforming to the 

 general curvature of the aperture ; lip simple. 



Distribution. Trias — Chalk. Europe, South Africa. The 

 cretaceous species are 14 in number. 



Etjlima. Sub-genus : — Leiostraca, H. and A. Adams [Balds, 

 Leach). 



Shell with a slight varix on each side of the spire. 



Distribution, 8 species. Mazatlan, Taboga. 



Acictjlena, Deshayes, 1864. 



Shell small, aciculated; apex laterally inclined; whorls 

 numerous, convex, smooth; aperture entire, small, subqua- 

 drangular; columella straight, narrow, cylindrical, and simple. 



Distribution, 6 species. Eocene. Paris basin. 



Mathilda, Semper, 1865. 



Shell turriculated, apex revolute, abruptly turned from left to 

 right ; whorls in the typical species transversely cingulated 

 and reticulated, longitudinally striated ; aperture entire, subro- 

 tund, base sometimes suberfuse ; lip acute ; columella smooth, 

 not plicated. 



Distribution. The type Turritella quadricarinatus, Brocchi, 

 is living in the Mediterranean, and is fossil in the Crag of 

 Anvers, and at Bologna. 



Fossil, 13 species. Eocene — . Europe, United States. 



Solenisctjs, Meek and Worthen, 1860. 



Etymology, solenisJcos, a little channel or gutter. 

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