larto the axis of the shell ; tip reflected nearly into the plane of the 

 aperture sharp, rather wide. 



Common full size, 1.45 inch long, .17 inch wide : of a large shell, 

 length 1.68 inch; breadth .175 inch; of a small shell, length 1.07 

 inch; breadth .16 inch : of a small entire shell, length 1.65. 



This species probably excels all other shells in the number of 

 "whorls. 



Cylindrella alba. Shell subfusiform, widest above the mid- 

 dle ; pure white ; strias scarcely visible under a common magnifier 

 except on the last two whorls ; the last whorl is sharply carinate an- 

 teriorly, rather obtusely carinate just above the middle ; spire with 

 rectilinear out nes ; apex truncate with the loss of thirteen or four- 

 teen whorls, the upper part of the spire before truncation being very 

 long and slender ; thirteen or fourteen whorls remaining, slightly con- 

 vex, with a well impressed suture ; last whorl much produced oblique- 

 ly ; aperture sharply angular anteriorly, obtusely so on the right, in 

 the rest well rounded ; lip moderately thickened, reflected nearly into 

 the plane of the aperture, shining, sharp, rather narrow. 



Length .4 inch ; breadth .083 inch. 



Var. striatula ; strire very distinct under a common magnifier ; 

 length .52 inch; breadth .11 inch. 



Cylindrella costulata. Shell subovate, but elongated; whi- 

 tish ; with thin very prominent very distant moderately oblique ribs, 

 of which there are about ten on the penult whorl, and which, as usual 

 in this genus, are more crowded on the last whorl, — anteriorly with a 

 prominent but not sharp carina ; spire with convex outlines along the 

 middle ; apex truncate with the loss of five or six whorls ; nine or ten 

 whorls remaining, rather flattened, but with a deep suture ; last whorl 

 much detached and producec^ angulated on the right ; aperture much 

 dilated on the right, anteriorly a little angular, the rest rounded ; lip 

 some what thickened, rather narrow and sharp, reflected into the plane 

 of the aperture. 



Length .25 inch; breadth .075 inch; length of an entire specimen 

 .325 inch. 



Cylindrella Montana. Shell subcylindrical, tapering above; 

 pale red, rarely white ; with closely set extremely fine oblique stris, 

 which are most arcuate above the middle, with a very small 

 rather prominent carina anteriorly, slightly angulated just above the 

 middle of the last whorl ; spire with convex outlines in the upper third, 

 in the rest rectilinear, above the place of truncation rectilinear up io 



