44 MISSISSIPPIAN BRACHIOPODA 



gin ; in the type specimen the greatest depth of the valve lies posterior to 

 the apex near the center and the central portion is depressed convex; 

 towards the margin the surface becomes concave, but this contour is 

 doubtless due to the strongly concave surface upon which this individual 

 has grown, and in other situations it would doubtless be depressed convex 

 throughout. Surface marked by rather fine, but more or less irregular 

 and uneven concentric markings. 



Remarks. It is not possible to compare this species with all the named 

 forms from these Mississippian faunas for the reason that several have 

 been described very briefly without accompanying figures. It seems to be 

 sufficiently distinct from all of them, however. 



Horizon. Fern Glen formation. 



CRANIA DODGEI Rowley 

 Plate I, Fig. 32 



1908. Crania dodgei Rowley, Mo. [Bureau Geol. and Mines, vol. 8, 2nd ser., 

 p. 73, pi. 17, figs. 5-6. 



Description. Shell below medium size, subcircular in outline, the holo- 

 type attached to a shell of Spirifer marionensis. The dimensions of the 

 holotype are : greatest diameter 17 mm., convexity of brachial valve 6 mm. 



Pedicle valve entirely covered by the brachial in the two specimens ex- 

 amined, apparently attached by its entire external surface. 



Brachial valve depressed conical, the apex subcentral or somewhat ec- 

 centric in position, erect or slightly inclined, the surface sloping in all 

 directions from the apex with a gently convex curvature. The surface 

 marked by rather strong, crowded, irregular, concentric lines of growth, 

 and by very fine, obscure, and interrupted radiating stria?. 



Remarks. Only a few examples of this species have been observed but 

 their irregular, crowded, concentric lines of growth with obscure radiat- 

 ing strise will serve to distinguish them from other species. 



Horizon. Louisiana limestone. 



CRANIA REPOSITA White 



Plate I, Figs. 25, 26 

 1862. Crania reposita White, Proc. Boston Soc. Nat. Hist., vol. 9, p. 30. 



Description. Shell small, subcircular, subelliptical, subovate or sub- 

 quadrate in outline, the types attached to a shell of Spirifer grimesi. The 

 dimensions of the largest of the type specimens are : greater diameter 13.5 

 mm., lesser diameter 11.1 mm. 



Pedicle valve firmly cemented by its entire external surface, its peri- 

 phery thickened in a ring-like marginal border; the anterior adductor 

 muscular scars contiguous, situated a little eccentrically and distinctly 



