160 Descriptions of Neiu Species and Varieties of Shells, 



convex, with a deep suture : aperture widely ovate, moderately 

 effuse : labrum rather thin, slightly reflected : linguiforrn part 

 obtuse, moderately produced laterally at the lower part of the 

 right side: labium a little thickened and reflected. 



Mean divergence about 15° ; length .32 inch ; greatest 

 breadth .11 inch ; least breadth .09 inch. 



Geomelania costulosa, G. exilis, G. Hilliana, and G. stri- 

 osa are as yet unique in the collection of the Hon. Edward 

 Chitty. G. conica is unique in the Zoological Museum of 

 Amherst College. 



CylindreUa Agnesiana, var. di.aiinuta. We are indebted 

 to Dr. A. Barrett for this remarkably small variety, with the 

 following dimensions : length after truncation .67 inch ; 

 breadth .22 inch. In the specimens before us the lip is but 

 slightly expanded. It inhabits Fiamstead, in the Port Royal 

 Mountains. 



Cylindrella Robertsi. Shell elongate, fusiform, widest 

 a little below the middle : pearl white : with, on each side of 

 the suture, a series of very short transverse prominent ribs, 

 which abruptly terminate so as to leave a large portion of the 

 middle of the whorls smooth ; ribs about fifteen on each 

 whorl ; the series below the suture being the larger ; both 

 series are continued on the two angles of the produced part 

 of the last whorl, over on the back part of which each rib is uni- 

 ted to its opposite by a small lamella : spire with the outlines 

 quite convex except in the upper third : apex truncate with 

 the loss of — whorls : whorlrs remaining nine or ten, planu- 

 late or slightly concave, with a dec]) suture ; last whorl widely 

 disjunct in its last third part from llie penult whorl, with an 

 angle on the right and another on the lower side : aperture 

 subangular above and below, more angular on the right : lip 

 rather thin, reflected into the plane of the aperture, moderately 

 expanded. 



Length .37 inch ; breadth .095 inch. 



