COAL-MEASUEE SPECIES. 339 



above; basal margin long, parallel to the hinge, nearly straight for most 

 of its length, or faintly sinuous near the middle, rounding up anteriorly, 

 and forming a more or less defined angle at its connection with the lower 

 part of the posterior margin behind; posterior umbonal slope distinctly 

 angular from the beaks to the angular posterior basal extremity, while 

 a second carina passes obliquely backward and downward along the 

 middle of the posterior dorsal space above the umbonal ridge of each 

 valve ; beaks depressed to the line of the cardinal margin, very little 

 projecting, and placed one-fifth to one-fourth the length of the valves 

 from the anterior margin. Surface marked by distinct concentric lines 

 of growth, that become strongly defined on the flanks and anterior parts 

 of the valves, but are less distinct on the space above and behind the 

 umbonal angles. 



Length, 1.10 inches; height, 0.52 inch; convexity, about 0.20 inch. 



This shell has very much the form and general appearance of Cypri- 

 cardia striato-lamellosa, DeKoninck, as figured in his An. Foss. Carb., Belg., 

 pi. H, figs. 8a., b, but its beaks are less prominent and not so curved for- 

 ward, and it seems to be entirely destitute of the deep lunule seen in 

 that shell. I have not seen its hinge, but one of the specimens (fig. 

 106), which is partly an internal cast, shows the impression of a long, 

 posterior, lateral tooth, and marks of a rather deep, anterior adductor 

 muscle, as in Pleurophorus. Judging from the distinctness of the surface 

 markings on the casts, it is probable that the shell itself is thin. 



Locality and position : Coal Measures, at Newark, Ohio. 



Genus SOLENOMY A, Lamarck, 1818. 



(Hist., v., 488.) 

 SOLENOMYA ? ? ANODONTOIDES, Meek. 



Plate 19, fig. n. 



Shell transversely elliptic-subovate, compressed, nearly twice as long 

 as high, with the greatest height a little behind the middle ; posterior 

 margin nearly regularly rounded in outline ; anterior extremity shorter 

 and more narrowly rounded than the other ; basal margin forming a broad, 

 semioval or semielliptic curve, being generally slightly more prominent 

 behind than in front of the middle ; dorsal margin presenting a nearly 

 straight, or very gently arched, outline from the beaks posteriorly, and 

 rounding into the posterior margin behind, while in front of the beaks 



