New Species of Devonian Fossils. 135 



the very small, elongate, and more deeply impressed adductor 

 scars. The diductor scars are marked by less distinct radiatingf 

 lines. Teeth small, supported by dental lamellae which are adnas- 

 cent to the thickened sides of the shell. In the dorsal valve 

 the cardinal process is very large, consisting of a thickened trunk 

 which ends anteriorly in a short low median septum, and pos- 

 teriorly it is cleft into two apophyses which are directed poste- 

 riorly and downward into the opposite valve. These apophyses 

 converge and unite into one at the beak on the posterior side. 

 The surfaces of attachment are medially grooved. From the 

 sides of the trunk of the cardinal process arise the stout short 

 crura. 



Surface marked by rather coarse striations crossed by exceed- 

 ingly fine concentric growth-lines. There is also an incipient 

 development of plications which appear only near the front 

 margins, being quite distinct in some specimens and scarcely 

 defined in others. They are low and rounded and separated by 

 rounded interspaces. There is a tendency to be four on the fold 

 and three on the sinus, with three fainter ones on each lateral 

 slope, but on some specimens the latter are very indistinct or 

 absent, while one large specimen shows only three plications on 

 the fold. There is a very slight median depression on the pos- 

 terior half of the dorsal valve. 



Di)ncnsioiis of an az'cragc specimen: Length, 23 mm.; width, 

 21 mm.; depth, 15 mm. 



Discussion: This species is nearest E. singidaris, but compared 

 with that shell it is much larger, proportionately narrower, its 

 fold and sinus are not so sharply defined, its striations are much 

 coarser, and it is distinctly characterized by its rounded plications. 

 Compared with E. peculiaris, it is much larger and broader in 

 the anterior portion, it shows a distinct median depression over 

 the dorsal umbo which that species does not have, its striations 

 are coarser, and there are internal differences in the muscle- 

 scars, the diductors being relatively larger and more quadrate 

 and the adductors in the ventral valve being relatively nearer the 

 beak. The new species is readily distinguished from this and 

 all other described species by its rounded hemiplications. 



Occurrence: Common in the Birdsong shale at Perryville, 

 various localities on Big Lick and Birdsong creeks, and especially 



