HEI.DKHBEIUi Fon.MATlOX FN MARYLAND 27 



supported by a strong median septum. These characters, when associated 

 with its external form, phice it in the genus Wilsonia. while the two 

 Helderbergian species mentioned possess well-developed cardinal proc- 

 esses and the other characters which distinguish the genus Uncinulus." 

 Weller, 1903. 



It occurs in the upper Decker Ferry of New Jersey. 



Occurrence. — Helderberg Formation, Keyser Membku. Cumber- 

 land, Cash Valley. 



Collection. — U. S. National Museum. 



WiLSOXiA CF. GLOBOSA Weller 

 Plate LXV, Figs. 18-20 



Description. — Shell transversely subelliptical to subpentagonal in out- 

 line, broader than long. Ventral valve convex, plano-convex to depressed 

 convex ; beak extending beyond that of the brachial valve and slightly in- 

 curved over it. Dorsal valve convex, more gibbous and consequently 

 more convex than the ventral valve, greatest convexity near the middle, 

 beak incurved under the beak of the ventral valve. Surface of each 

 valve contains indistinct, low, rounded, simple radiating plications, 

 which can only be seen from, the center anteriorly and become more 

 conspicuous towards the front. From the center of the shell to the beak 

 the surface is smooth save for indistinct concentric lines of growth. An- 

 terior slope abrupt; lateral margins abruptly deflected posteriorly and 

 rounded towards the anterior margin. Fold and sinus scarcely if at all 

 developed. 



Dimensions, 11 mm. long and 13.5 mm. wide, 



A single somewhat imperfect individual has been observed which has 

 been described above. It may be compared with If. globosa from which 

 it differs in a number of respects. 



Occurrence. — Helderberg Formation ? Keyser Member? Tonoloway. 



Collection. — Maryland Geological Survey. 



