BRACHIOPODA. 351 



Streptorhynchus Ulrichi, sp. IIOV. 



PLATE Xlis, FIG. 15. 



Shell of comparatively large size for this genus. General contour subtrihedral. 

 Hinge-line shorter than the greatest diameter of the valves. Cardinal area 

 high, somewhat incurved and distorted; sides considerably shorter than the 

 base. Deltidium broad. Marginal outline of the pedicle-valve, from hinge- 

 line forward, semiovate, somewhat irregular, contracted toward the hinge 

 and expanding in the pallial region. The interior of the pedicle-valve shows 

 strong teeth, the dental lamellae extending downward and enclosing the 

 posterior portion of an ovate muscular scar. There is no median septum. 

 External surface convex in the upper part becoming depressed toward the 

 anterior margin; quite irregular in growth, being crossed by more or less 

 conspicuous concentric ridges or varices ; covered with numerous fine radi- 

 ating, subequal striaB which increase by implantation. 

 Brachial valve not known. 



Chester limestone. Crittenden comity, Kentucky. 



Christiania subquadrata, sp. nov. 



18S3. Leptcena subquadrata. Hall. Rept. State Geologist N. Y. for 1882, pi. (xv) 46, tigs. 32, 33. 

 PLATE XV, FIGS 32,33; PLATE XVa, FIG. 36; PLATE XX, FIGS. lS-20. 



Shell small, elongate, semielliptical in outline, strongly convexo-concave. 

 Hinge-line short, straight, not equaling the greatest diameter of the valves 

 anteriorly. In the pedicle-valve the umbo is full, rounded and incurved, 

 with the apex obscure ; the cardinal area is moderately broad and bears an 

 open delthyrium which terminates above in a circular foramen. The teeth 

 are short, divergent and continued into ridges which form the lateral mar- 

 gins of two linguiform, muscular scars, traversing the shell for almost its 

 entire length. These scars enclose two much shorter impressions. In the 

 brachial valve the area is narrow, the cardinal process bipartite on its an- 

 terior face, each of the lobes being grooved behind. The crural plates are 

 very long and divergent, the upper portion of each terminating in an elevated 



