210 PROCEEDINGS OF THE MALACOLOGICAl SOCIETY. 



CJiondropoma BaTiamense, Shuttleworth, and C. Hawsoni, Pfeiffer, 

 of the Bahamas, Tudora Morelefiana, Petit, Isle of Pines, and 

 T. excurrens, Gundlach, Cuba, belong to this group. The tube 

 communicates with the whorl, so that air is admitted when the 

 aperture is hermetically sealed by the operculum. In senile specimens 

 it is sometimes closed by shelly matter deposited within the whorl. 

 The end of the short, bulb-shaped tube has the aperture turned 

 toward and very close to the surface of the preceding whorl, which is 

 probably the reason why the arrangement has not attracted more 

 attention. The tube is complete before the outer lip or its expanded 

 portion is begun, and thus differs from the sulcus or channel at the 

 posterior angle of the aperture and indenting the lip itself, which 

 occurs in some American members of this family. 



It is hardly necessary to add that in the above diagnoses account 

 has been taken only of the distinctive and diagnostic characters. 

 I have depended on the identifications of species made by Bland and 

 Gundlach of specimens in the JS^ational Museum. 



