FOSSILS OF THE COAL MEASURES. 583 



Genus EDMOXDIA. 

 EI>MOM>IA> PEROBLOXGA, M. and W. 



PL 27, Fig. 4. 



Edm>.iit<li .' peroblontja, MKEK and "WOKTHEX, 1866. Proceed. A cad. Xat. Sci., Phila., (for Dec. 1865,) 



1>. -!!'.'. 



SHELL longitudinally oblong, the length being about 

 double the hight, very inequilateral, moderately convex; 

 the greatest convexity being along the oblique umbonal 

 slopes, above and below which the valves are cuneate 

 postero-dorsally and antero-veutrally. Posterior side dis- 

 tinctly compressed near the extremity, its margin somewhat 

 rounded or sub-truncate in outline; anterior side very short, 

 less compressed and rather more narrowly rounded than the 

 other: basal and dorsal margins nearly straight and parallel, 

 the former being very slightly convex in outline a little in 

 advance of the middle. Beaks near the anterior end, very 

 oblique, compressed, and but slightly elevated above the 

 hinge margin; umbonal slopes prominently rounded or sub- 

 angular from the beaks obliquely towards the posterior 

 inferior margin. Surface of cast showing only faint traces 

 of a feAv irregular concentric undulations, mainly below 

 the umbonal ridge. (Hinge and interior unknown.) 



Length, 2.50 inches; hight, 1.25 inches; convexity of a 

 left valve, 0.47 inch. 



Although the only specimen of this species we have seen is merely a 

 cast, showing nothing of the hinge, or the internal characters, nor of the 

 finer surface markings, we have thought it desirable to call attention to 

 it as one of the bivalves of this horizon, as it -will probably be long 

 before better examples are found. We confess, however, that we are at 

 a loss in regard to its generic characters, and have merely placed it pro- 

 visionally in the genus Edmondia. 



In general appearance, this shell approaches Eilmonflia ? conqn-essa 

 of McCoy. (Carb. Foss. Ireland, pi. 13. fig. 10,) but it is rather longer in 

 proportion to its hight, and it has much less prominent and more com- 

 pressed beaks, as \\ell as sub-angular, instead of obtusely rounded mn- 

 boiial slope-. 



