540 Systematic Paleontology 



Occurrence. — Oriskany Formation, Shrr^er Member. 21st Bridge, 

 Cash Valley. 



Collectiotis. — Maryland Geological Survey, U. S. National Museum. 



Cr^vterellina oblonga n. sp. 

 Plate XCVIII, Fig. 20 



Description. — Carapace suboblong or somewhat irregularly subovate; 

 posterior end slightly narrower and more rounded than the blunt anterior 

 end ; anterior half of valve with a ring-like ridge enclosing a depression 

 from the center of which a small, rounded, cone-like prominence arises. 

 Otherwise the surface is simply convex, with occasional scattered punctag, 

 or smooth. 



This species is readily distinguished from its associate C. rohustahj its 

 smaller size, more elongate shape and proportionately smaller " crater." 



Length of right valve 0.8 mm. ; height 0.5 mm. 



Occurrence. — Oriskany Formation. Shriver Member. 21st Bridge, 

 Cash Valley. 



Collections. — Maryland Geological Sun^ey, U. S. National Museum. 



Family CYPRIDAE 



Genus BYTHOCYPRIS Brady 



BYTHOCYrnis punctulata var. arctatum n. var. 



Plate XCVIII, Fig. 22 



Description. — The specimen upon wliich this new variety is founded 

 agrees apparently fairly well with the Middle Devonian Bj/thocypris 

 punctulata Ulrich, but close comparison will show the following differ- 

 ences: The new variety is smaller, more elongate and narrower at the 

 anterior end, but a more striking difference is observed in the close 

 arrangement of the punctae. In B. punctata, the punctae are several times 

 their own diameter apart, but in the variety this distance is reduced to 

 one diameter or even less. 



Length of left valve 1.10 mm. ; height .GO mm. 



Occurrence. — Heldeeberg Formation, Keyser Member. Cumber- 

 land, Maryland ; Keyser, West Virginia. 



Collections. — Maryland Geological Survey, U. S. National Museum. 



