MARYLAND GEOLOGICAL SURVEY 709 



obscure; pallial sinus linguiform, symmetrically rounded, obliquely 

 ascending not reaching the median vertical of the shell. 



Dimensions. Altitude 15 mm., latitude 21 mm., diameter 10.2 mm. 



Type Locality. Krightseat, Prince George's County. 



Cymbophora berryi is characterized by its rather small size, evenly 

 inflated valves and regular ovate-trigonal outline. 



This prominent member of the Monmouth fauna is named for Prof. 

 Edward W. Berry of Johns Hopkins University. 



Occurrence. MONMOUTH FORMATION. Brightseat, Brooks estate near 

 Seat Pleasant, 1 mile west of Friendly, 2 miles south of Oxon Hill, Fort 

 Washington, Prince George's County. 



Collection. Maryland Geological Survey. 



SL'ISULA (CYMBOPHORA) WORDENI n. sp. 

 Plate XLIII, Figs. 4, 5 



Description. Shell rather large, not very thin but very fragile, trigonal 

 in outline, moderately inflated; umbones submedial, well rounded, the 

 apices full, incurved, prosogyrate ; umbonal angle not far from 90, dorsal 

 margin very steep, the anterior oblique, the posterior feebly convex ; maxi- 

 mum latitude of shell very near the ventral margin ; lateral margins very 

 short, squarely truncate ; ventral margin feebly but evenly arcuate ; both 

 anterior and posterior areas cut off by obtusely angulated carince, the 

 anterior outlined by a linear sulcus, the posterior by an irregular raised 

 line which marks the anterior boundary of a roughened area which origi- 

 nates at the umbones and gradually widens so that its wider extremity is 

 coincident with the posterior lateral margin; anterior area and posterior 

 portion of posterior area quite sharply sculptured incrementally; sculp- 

 ture on medial portion of disk restricted to rather inconspicuous and 

 irregular incremental^ hinge armature rather concentrated, the hinge 

 plate extending less than half-way down the margin ; ligament internal, 

 lodged in a scoop-shaped chondrophore with very strongly upcurved 

 edges; right cardinals diverging at an angle of a little less than 90, fused 

 at the umbonal extremity of the anterior dorsal margin ; lateral lamina 1 



