72 HOLOSPIRA. 



c. Penult, whorl with a short axial and a basal lamella 

 only. Sect. Distomospira, sp. no. 8. 



d. Penult, whorl with a short axial lamella only. 



Sect. Haplostemma, sp. no. 12, 13. 



J. . e. A low plait or spiral swelling extending throughout 

 the cylindrical portion of the shell, a short lamella 

 superposed upon it in the penultimate whorl. 



Sect. Bostrichocentrum, sp. no. 9-11. 



II. Internal column smooth; interior without lamellae or 

 plaits of any kind ; last whorl normal, straightened ante- 

 riorly; aperture without folds or other obstruction. 

 Whorls 11 to 19. Subgenus HAPLOCION, sp. no. 14-20. 



III. Internal column smooth; interior without lamellae; last 

 whorl sinuous, turning sinistrally ; aperture oblong, with 

 a strong fold within the right margin and a columellar 

 callus in the throat. Whorls 12 to 14. 



Subgenus METASTOMA, sp. no. 21. 



IV. Internal column vertically ribbed, large. Whorls narrow 



and numerous (17-21) ; terminal cone short. 



Subgenus COELOSTEMMA, sp. no. 22-24. 

 V. Internal structure unknown. Species no. 25-28. 



Subgenus HOLOSPIRA s. str. 



Internal column bearing a spiral lamella or plait within the 

 penultimate whorl, or with additional lamellae upon the roof, 

 floor or outer wall of the same whorl. 



This is the most numerous subgenus in species, but all of the 

 forms seem from present data to be excessively restricted in 

 distribution. 



Section Holospira. 



Cavity of the penultimate whorl obstructed by four spiral 

 lamellae, none of them exceeding a whorl in length: a colu- 

 mellar lamella, a large (parietal) lamella on the roof of the 

 whorl, a smaller (basal) one on the floor of the whorl, and a 

 palatal plait, usually the smallest and sometimes wanting, on 

 the outer wall. Teeth of the radula more numerous than in 

 other sections of the genus. Type H. pilocerei. 



Six species with the structure of this group are now known 



