GIRTT, NEW CARBONIFEROUS FOSSILS 2-25 



allel with the hinge, curving up rather strongly in front. Anterior outline 

 concave above for about one third the height, rather strongly convex below, 

 more abruptly rounded near the emarginate portion. Posterior outline some- 

 what obscurely truncated in a broken line. The upper truncation, which 

 covers about one half the height, is very oblique, while the lower is nearly 

 perpendicular to the lower margin. No distinct angles are formed where the 

 lines join. The convexity is high. The beak, rather small and strongly in- 

 curved, is situated but a short distance posterior to the margin. The umbonal 

 ridge is strongly elevated and angular. A second distinct, though not very 

 prominent ridge divides the post-cardinal slope longitudinally, and the shell 

 is abruptly inflected near the cardinal line to form a large, long escutcheon 

 with sharply angular outlines. The post-cardinal slope is somewhat com- 

 pressed, as is also the anterior portion. A broad, shallow constriction occurs 

 just in front of the umbonal ridge. 



The surface is marked by regularly arranged, moderately fine and deep con- 

 centric stri!^. which toward the front and back, and possibly all over when 

 the preservation is good, are separated by rather thin, high, concentric lirse. 

 Traces of fine radial lirse have been seen on the post-cardinal slope of one or 

 two small specimens. 



There is a large subcircular anterior scar. 



Sphenotus dubium sp. nov. 



Shell small, transverse, subquadrate. Greatest width twice the greatest 

 height. Beak about one fourth the width posterior to the margin, small, 

 strongly incurved. Convexity high, somewhat compressed posteriorly. Um- 

 bonal ridge rounded. Mesial portion, or the portion just anterior to a line from 

 the beak to the middle of the base, somewhat flattened or slightly depressed 

 into a broad, shallow constriction. Anterior extremity bent inward and down- 

 ward to form an elongated lunule with very sharply defined, angular border. 

 A long narrow escutcheon is similarly formed along the margin behind the 

 beak. The post-cardinal slope descends somewhat abruptly and is divided 

 longitudinally by a more obscure ridge. 



The hinge line is straight nearly three fourths the entire width of the shell. 

 The lower margin is gently convex, straightened thi'ough the middle, sub- 

 parallel to the hinge, but bent upward behind, so that this end is distinctly 

 narrower than the other. Posterior extremity truncated by a nearly straight 

 outline very slightly oblique, making a distinct cardinal angle somewhat 

 greater than 90°. Anterior outline abruptly truncated by the nearly straight 

 oblique line formed by the flexure of the shell which produces the lunule; 

 sharply rounded below. 



Surface marked by rather strong, more or less irregular and unequal con- 

 centric stripe, which are distinctly weaker over the post-cardinal slope, and by 

 fine papillfe which tend to have a radial arrangement. 



Sphenotus? meslerianum sp. nov. 



Shell rather small, subcuneate, transverse. Greatest height a little less 

 than half the extreme width. Strongly convex; umbonal ridge snbangular. dis- 

 tinct. Post-umbonal slope somewhat compressed. A slight constriction de- 



