MARYLAND GEOLOGICAL SURVEY 289 



ujjper side of the first ridge, and is moderately impressed ; spaces between 

 the ridges crossed by more or less elevated irregular lines, or coarse striae 

 of groAvth; last ivhorl on the upper half, sculptured as the spiral whorls 

 with a fifth smaller revolving line on the lower part; aperture ovate, 

 one-eighth of the length of the shell, the line of its length making an 

 angle of about 25° with the axis of the shell; lahrutn thin; canal rather 

 more than a third as long as the aperture, turning to the left." Adams, 

 1840. 



The question as to the name of this has been discussed in detail by 

 Dr. Dall, but the question is further complicated by the possible equiva- 

 lency of Cerithium clavulus H. C. Lea. If the Virginia Miocene species, 

 clavulus, is the same as the recent species, terebrale Adams non Lamarck, 

 then clavulus will have priority, as it dates from 184:3, while the foot- 

 note in which Lea j^roposed adamsii as a substitute for terebrale Adams 

 was omitted from the 18 i3 edition of Lea's paper and did not ajDpear 

 until two years later. 



Length, 8 mm. ; diameter, 2.5 mm. 



Occurrence. — Choptank Formation. Dover Bridge, Greensboro, 

 Cbrdova, Jones Wharf. Calvert Formation. Plum Point, Church 

 Hill, 3 miles west of Centerville. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 U. S. National Museum, Cornell University. 



Genus CERITHIOPSIS Forbes and Hanley. 



Cerithiopsis calvertensis n. sp. 

 Plate LV, Fig. 7. 



Description. — Shell small, elongate, pyramidal, fragile, many-whorled ; 

 suture distinct, deep; four broad revolving ridges with broader inter- 

 spaces crossed by about thirty raised longitudinal ribs which granulate 

 the spirals at their intersection ; the lower revolving ridge hidden by the 

 succeeding whorl of the spire ; base smooth, except for lines of growth. 



This species may be readily distinguished from the following by having 

 four revolving ridges almost equal in size instead of only two prominent 

 ones, and by having the ridges less strongly nodular. 



Length, 8 mm. ; diameter, 2.5 mm. 



