82 



of P. jmlchra^ of the same size, have five teeth well developed, as 

 have also the least of our specimens of P. n'ltida. 



Greatest breadth .21 inch ; least breadth .13 inch ; heisrht .08 inch. 



Cylindrella Greyana. Shell much elongated, tapering quite 

 uniformly to the apex : dingy white : with excessively elevated 

 lamellar transverse ribs, of which there are six on each whorl ; with 

 the intercostal spaces densely covered with microscopic spiral strias : 

 spire with the outlines nearly rectilinear : apex broadly truncate with 

 the loss of five whorls, of which the first one and one-half are smooth, 

 the next one is closely covered with microscopic transverse raised 

 lines, and the rest have twelve to fourteen lamellar transverse ribs, 

 which are moderately elevated, but which increase in size and dimin- 

 ish in number down the spire to a little below the place of trunca- 

 tion : remaining whorls about seven, somewhat flattened, with a very 

 deep suture ; last whorl small, scarcely produced from its last point 

 of contact with the penult whorl : aperture obliquely ovate, a little 

 modilied by the penult whorl : labrum near the last rib, very thin and 

 sharp, not reflected. 



Length .31 inch; breadth .14 inch. 



This extraordinary shell is dedicated to His Excellency, Sir 

 Charles Grey, the present Governor General of Jamaica, as a tribute 

 of respect for those attainments in Natural Science, which adorn a 

 high olhcial station. We thus also commemorate the administration, 

 during which a very large portion of the land and fresh-water shells 

 of Jamaica have been discovered. 



Cylindrella lata. Shell very robust, cylindrical in the lower 

 three-fourths, rapidly tapering above : wax color, with a dark brown 

 line next below the suture : with excessively minute crowded trans- 

 verse stria3 ; anterior spiral keel very prominent : apex not very 



broadly truncate, with the loss of whorls: whorls remaining 



eight and one-third, very narrow, slightly convex, with a lightly im- 

 pressed suture: aperture considerably produced beyond the penult 

 whorl, transversely elliptical : lip broadly reflected. This species in 

 several respects combines the characters of C. sanguinea and C rosea. 



Length .86 inch ; breadth .33 inch. 



Cylindrella Hollandi. Shell rather slender, cylindrical in 

 the lower three fourths, slowly tapering above: wax color: with very 

 minute crowded transverse striie, and the anterior spiral keel not very 

 prominent : apex rather broadly truncate, with the loss of 



