sculptured with distant prominent very slender ribs, which are not 

 impressed by the very numerous microscopic spiral stri», of which 

 about twenty are visible on the whorls of the spire : spire with near- 

 ly rectilinear outlines ; apex truncate with the loss of whorls; 



seven whorls remaining, quite convex, with a very deep suture ; ap- 

 erture ovate, moderately eiFuse ; labrum moderately thickened andre- 

 j6ected, and but little produced at the lower part ; labium prominent* 

 rather thick, slightly detached from the penult whorl at the very small 

 sinus above which it unites with the labrum. 



Mean divergence W^ to 14°; length .3 inch; greatest breadth .08 

 inch ; least breadth .07 inch. 



Cylindrella Beardsleana. Shell quite regularly conic, but 

 much elongated ; whitish ; with closely set small obtuse ribs which are 

 not oblique, not carinated anteriorly ; spire with rectilinear outlines ; 

 apex truncate with the loss of six whorls ; eight whorls remaining, 

 quite convex, with a deep suture ; last whorl a little detached, angular 

 above ; lip sharp, reflected opposite to the penult whorl, otherwise 

 scarcely reflected. 



Length .3 inch ; breadth .07 inch. 



C. pgymaea Ad. Jan. 1. 1845, is similar, but its aperture is wider, 

 the whorls more convex with a deeper suture, and the shell is much 

 smaller. 



Cylindrella Agnesiana. Shell sinistrorsal, very long, cylin- 

 drical in the lower two-thirds, moderately tapering above ; white ; 

 with very oblique very closely set fine rather sharp strice which are 

 more oblique in their upper part, — anteriorly with an extremely 

 prominent and acute carina, on the left side of the last whorl with a 

 carina scarcely less prominent and acute, on the upper side with a 

 third carina quite acute and prominent, on the right side subangular ; 

 spire with outlines mostly rectilinear, with a waved axis at the tip ; 

 apex broadly truncate with the loss of twelve whorls ; eighteen to 

 twenty-two whorls remaining, the usual total number being thirty ; 

 ( a short entire specimen has twenty-eight ; ) whorls flattened or 

 scarcely convex, with a moderately impressed suture ; last whorl 

 very much produced obliquely; aperture angulated in proportion to 

 the sharpness of the carinae, trapezoidal, the upper left side being the 

 longer ; with one diameter parallel and the other nearly perpendicu- 



