INSTITUTE OF SCIENCE, PHILADELPHIA. 40 1 



Shell elevated-conical, rather acute, with seven and a half whorls, of which 

 two comprise the minute smooth nucleus, two and a half more are reticulately 

 and the rest spirally sculptured; earlier whorls with three or four flat, close- 

 set, rather wide spirals cut by radiating lines so as to be chequered or obso- 

 letely reticulated ; as the whorls increase the spirals merge in the general 

 smooth surface, and the grooves which separated them are continued as 

 impressed lines which become quite faint on the last whorl ; base with eight 

 or more flat weak spirals, stronger near the pillar ; there is no umbilical pit 

 or groove; the periphery is rounded; the suture very distinct, but not chan- 

 nelled ; the whorls slightly convex, the aperture ovate-quadrangular. Alt. 

 10 ; max. diam. 9 mm. 



This is a very simple little shell, easily identified by the microscopic sculpt- 

 ure of the earlier whorls, which, except when examined under a glass, is likely 

 to be unnoticed. 



Calliostoma labrosum Conrad. 

 Trochiis labrosus Conrad, Journ. Acad. Nat. Sci. vii. p. 138, 1834. 

 Zizyphinus labrosiis Conr., Proc. Acad. Nat. Sci. 1862, p. 569. 



James River, Va., in the Chesapeake Miocene. 



This species recalls T. liumilis Conrad, which is umbilicate, and C. virgin- 

 ?'«/;«, which is a more elevated shell. In C. labrosum the minute one-whorled 

 nucleus is smooth, the next two whorls are furnished with three strong 

 rounded spirals occupying the whole surface between the sutures ; these 

 become less prominent and the adult sculpture comprises a channelled periph- 

 ery, of which the two ribs are rounded and the lower one more prominent, a 

 strong spiral a little in front of the appressed suture, which latter runs just 

 below and is slightly overshadowed by the lower peripheral keel ; the top of 

 the later whorls is impressed as in C. virginicwn, but this channel is smooth, 

 polished and sculptured, usually by distant impressed lines which become 

 more numerous with age; the base is flattish, polished, with two very strong 

 spirals near the pillar, no umbilical pit, numerous fine striae near the periphery 

 and smoother middle area; the whole shell is low, with a rather pointed apex. 

 Alt. 7 ; max. diam. 9.5 mm., in a specimen not quite mature. 



I have not found any figure of this species, and therefore describe its 

 characters more in detail that others may identify it. The specimen in the 

 National Museum was named by Conrad. 



Oalliostoma Harrisil n. s. 

 Plate 18, figure 6. 

 Chesapeake Miocene of Yorktown and Bellefield, York River, Virginia, 

 collected by Mr. Gilbert D. Harris, of the U. S. Geological Survey. 



Shell wide, conical, with the sides of the spire rectilinear and the periph- 

 ery subangulate, six-whorled ; nucleus smooth, srriall, blunt, of two whorls ; 



