MARYLAND GEOLOGICAL SURVEY 365 



Length, 13 mm.; width, 6 mm.; diameter, 2 mm. 

 Occurrence. — Choptank Formation. Jones Wliarf, Dover Bridge, 

 Greensboro, Cordova. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



Genus CRENELLA Brown. 



Crenella virida n. sp. 



Plate XCVII, Fig. 4. 



Description. — Shell very small, thin, delicate, of pearly gray luster, 

 elongated ovate in shape, elevated ; beak projecting and sharply rounded ; 

 margins gracefully curved ; ladial scupture of fine, close-set, narrow, 

 rounded, raised lines, their number increasing by dichotomy and by in- 

 tercalation between older lines. 



As compared with C. dupliniana this species is more elongated, less 

 elevated, less robust, has coarser sulcations and these sulcations are more 

 branching than in C. dupliniana. 



Length, 1.65 mm. ; width, 1.25 mm. 



Occurrence. — Choptank Formation. Greensboro. 



Collection. — Maryland Geological Survey. 



Crenella gubeunatoria n. sp. 

 Plate XCVII, Fig. 5. 



Description. — Shell small, stout, rounded ovate, anteriorly broadened; 

 shell depressed; beak rounded and projecting very slightly; radial sculp- 

 ture prominent and coarse, ridges flattened and with narrow interspaces, 

 some being dichotomous, other added ribs are intercalated between previ- 

 ously existing ones. 



This is a less elevated, more rounded, more coarsely sculptured and 

 stouter species than C. virida. 



Length, 1.72 mm.; width, 1.5 mm. 



Occurrence. — Choptank Formation. Governor Eun. 



Collection. — Maryland Geological Survey. 



