MARYLAND GEOLOGICAL SURVEY 257 



Occurrence. CHAMBERSBURG LIMESTONE (Christiania bed). Appa- 

 lachian Valley of Pennsylvania., Maryland, and Virginia. 

 Bysedorph conglomerate at base of Trenton, Xew York. 

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



CHRISTIANIA LAMELLOSA n. sp. 

 Plate XLIX, Figs. 3-10 



Description. The strongly lamellose surface of this brachiopod is 

 sufficient reason for discriminating it from all other described species of 

 the genus. The general outline of the shell is not unlike several small 

 shells of the Chambersburg and early Trenton rocks referred to both 

 Christiania and Plectambonites, but the interior of the valve shows the 

 characteristic markings of the former genus. The pedicle valve is strongly 

 convex and bears the concentric lamellae almost to the beak. The 

 brachial valve is as strongly concave, with a smooth surface. The average 

 shell is 9 mm. high and about 10 mm. wide. 



Occurrence. MARTINSBURG SHALE (Sinuites bed). Southern Penn- 

 sylvania; also abundant at the same horizon in northern Virginia, the 

 types being from Strasburg. 



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



Genus LEPTAENA Dalman 



LEPTAENA CHARLOTTAE Winchell and Schuchert 

 Plate XLI, Figs. 11-13 



Leptaena cnarlottae Winchell and Schuchert, 1892, Amer. Geol., vol. ix, 



p. 288. 

 Leptaena charlottae Winchell and Schuchert, 1893, Geol. Minnesota, vol. iii, 



p. 410, pi. xxxii, figs. 1-5. 

 Strophomena halli Sardeson, 1892, Bull. Minnesota Acad. Nat. Sci., vol. iii, 



p. 334, pi. iv, figs. 36, 38. 



Description. " Shell small, transversely semioval, plano-convex, ge- 

 niculate, with the sides slightly convex and converging to the broadly 

 rounded front, or drawn out tongue shaped; hinge-line as long as, or 



