318 S. WELLER FAUX A OF THE FERN GLEN FORMATION 



DIELA8MA FERXGLEXEXSIS n. sp. 

 Plate 14, figure 7 



Description. — Shell large, subovate in outline, narrower posteriorly, 

 the greatest width anterior to the middle of the shell; shell structure 

 finely punctate. Pedicle valve badly crushed in the type specimen, but 

 apparently moderately convex, with a prominent arched beak perforated 

 by a large foramen. Brachial valve probably about as convex as the 

 pedicle. Both valves marked by several moderately strong lines of 

 growth toward the margin. 



The dimensions of the type specimen are: Length, 55 millimeters; 

 width, 43 millimeters; thickness, probably from 20 to 25 millimeters 

 originally, in the undistorted specimen. 



Remarks. — This species is represented in the collections by a few frag- 

 mentary or badly crushed and distorted specimens only, so that its char- 

 acters can not be entirely made out. It is characterized, however, by its 

 large size, and differs from other members of the genus of similar size in 

 the Mississippian faunas in its more broadly ovate form and the moderate 

 convexity of the. valves. 



MOLLUSC A 



PELECTPODA 



AYICULOPECTEX FERXGLEXEXSIS n. sp. 



Plate 15, figure 19 



Description. — Shell but slightly oblique, higher than wide, the great- 

 est width near the middle. Body of the shell, exclusive of the auricula- 

 tions, ovate in outline, rather strongly convex in the right valve, which 

 is the only one known. Posterior auriculation depressed convex, sharply 

 defined from the body of the shell, the postero-cardinal angle acute, the 

 posterior margin nearly straight, separated from the posterior margin of 

 the body of the shell by a subangular sinus of moderate depth. Anterior 

 auriculation not preserved, but apparently more sharply separated from 

 the body of the shell than the posterior one. Surface of the shell marked 

 by narrow, sharply angular, radiating costa?, which are narrower than 

 the intervening furrows and which are more or less alternating in size ; 

 the costse grow regularly smaller in size toward the posterior cardinal 

 extremity and are present upon the posterior auriculation; their charac- 

 ters anteriorly are not known, but they probably also cover the anterior 

 auriculation. Besides the radiating costEe, the surface is covered with 

 very fine raised concentric lines, and at intervals by strong, concentric 



