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carinated race , also a longitudinally ribbed race aiid one 

 with obsolete or nearly obsolete longitudinal ribs. The 

 size and form of the einbryonic tip differs (accordiug to 

 the uutrition of the embryo in the ovicapsule) in different 

 specimens of the sanie species. In one specimen it may be 

 twice as large as in the next specimen and varies in the 

 relative dimensions of its cone. The operculum is in this 

 genus extremely variable and often absent entirely. Of a 

 peck of B. cyaneum var. Mörchianum (wich is the dwarf 

 race of cyaneum with developed carinae and obsolete longi- 

 tudinal ribs) five percent had no operculum aud in many 

 of these even the opercular gland was absent. In the larger 

 species it is somewhat more constant, but the Situation 

 of the nucleus , in a five gallon keg of B. hydrophanum 

 Hancock was from quite central to nearly on one edge, 

 the form from olive shaped to quadrangular and frequently 

 nearly circular. Of this keg of 200 or 300 specimens there 

 were only seven males; all dwarfs. 



There is also another character which varies with the 

 sex, that is, the roundness or flatness of the top of the 

 whorls and by consequence the slope or turreted character 

 of the spire. The large eggmass requires a greater capacity 

 than the (also disproportionately large) penis of the male, 

 consequently the female shells are always more rounded 

 than the males even when of the sarae size aud, if the 

 reflected lip be formed at the gravid period , it will be 

 wider and more broadly reflected behind, than in a male 

 or in a female who has discharged her eggs before forming 

 the reflected lip. 



Of other characters the epidermis may vary also with 

 other features from velvetty and ciliated , to glossy and 

 smooth in the same species. It will usually in quite per- 

 fect specimens of the carinated races be found to be fringed 

 or prolonged on the edge of the carinae. B. ciliatum Fabr. 

 offers excellent examples of this. 



