Mr. W. H. Benson on the genus Alycseus, Gray. \77 



c. Subtrochiform. 

 sculptilis, B. Tube mediocre. Pegu. 



d. Depressed. 



umbonalis, B. Tube elongate. Pegu. 

 Physis, B., n. s. Tube elongate. Darjiling. 

 prosectus, B. Tube mediocre. Khasia Hills, 

 armillatus, B. Tube short. Pegu. 



Sect. 2. Charax, B. 



Constriction broad, contiguous to the aperture, and divided 

 more or less remotely from it, across the whorl, by a ridge which 

 is hollow internally. 



a. Depressed. 

 * Ridge curved back remotely from the peristome. 

 hebes, B. Tube mediocre. Khasia Hills. 

 Gemmula, B., n. s. Tube mediocre. Darjiling. 



** Ridge parallel to and approaching the peristome. 

 stylifer, B. Tube mediocre, Darjiling. 

 spiracellum, A. Ad. Tube short. Borneo, 

 strangulatus, Hiitt. Tube short. West Himalaya. 



*** Ridge parallel with and close to the base of the peristome. 

 plectocheilus, B., n. s. Tube mediocre. Darjiling. 



Sect. 3. Dioryx, B. 

 Constriction naiTOw, and immediately behind the aperture ; 

 the sutural tube arising proportionally nearer to the peristome 

 than in Sections 1 and 2. 



a. Globose- or ovate-conical. 

 Amphora, B. Tube very long. Tenasserim. 

 Urnula, B. Tube mediocre. Darjiling. 

 ? distortus, Haines. Tube not described. Siam. 



h. Depressed-turbinate. 

 crenulatus, B., n. s. Tube elongate. Darjiling. 



The names will help the memory, — Charax being a rampart, 

 Dioryx a fosse or ditch. There is a disposition in the ridge of 

 strangulatus to subside into the ordinary tumidity of the first 

 section, and thus to unite Sections 1 and 2 : but the ridge is 

 often sharply defined, and shows the internal sulcus distinctly. 



Alyctem distortus is imperfectly described by Haines, but is 

 inserted provisionally in Dioryx with reference to the character 

 " prope aperturam constricto," although said to be allied to A. 

 gibbus. 



Ann. ^ Mag. N. Hist. Ser. 3. Vol. iii. 12 



