MARYLAND GEOLOGICAL SURVEY 133 



tion in being more globular, and in having a shorter spire." Whitfield, 

 1894. 



The specimens here referred to this species may be characterized as 

 follows : 



Shell twice as long as broad ; mouth one-half the length of the shell ; 

 spire one-third the length of the shell; spire turreted, the later whorls 

 regularly increasing in height; surface polished; lines of growth faint, 

 slightly but uniformly convex toward the mouth; impressed revolving 

 lines increasing in width and proximity toward the base of the whorl, 

 with an intermediate revolving line most prominent in the middle of the 

 whorl, principal revolving lines strongly punctate because of narrow 

 raised longitudinal lines (of growth ?) which cross them. 



The essential characteristics are that the striae are alternate and are 

 obsolete above the middle of the whorl. It differs from A. punctostriatus 

 in being larger, more slender, and in having a larger part of the surface 

 covered with the revolving striae. 



The tj^pe of A. shilohensis has a strongly turreted spire and no puuct^e 

 in the revolving stri^. If this is constant it makes the species distinct. 



Act(eo7i semistriatus Ferussac has a strong resemblance to this form 

 and is possibly identical with it. If so, Ferussac's name will have jni- 

 ority. This question cannot be decided without authentic specimens. 



Length, 10.5 mm.; diameter, 5.5 mm. 



Occurrence. — St. Mary's Formation. Cove Point, Langley's Bluff. 

 Calvert Formation. Plum Point, 3 miles south of Chesapeake Beach. 



Collections. — Maryland Geological Survey, Johns Hopkins Univer- 

 sity, U. S. National Museum. 



ACT.EON CALVERTENSIS U. Sp. 



Plate XXXIX, Fig. 5. 



Description. — Shell small, ovate and somewhat globose, loosely coiled, 

 almost umbilicate, five-whorled; body whorl with about fourteen broad, 

 almost flat, revolving ribs with narrower deeply-set grooves between 

 them; lines of growth distinct and regular; surface polished. 



Length, 4,5 mm. ; diameter, 3 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collection. — Cornell University. 



