126 Carl O. Dunbar, 



Discussion: This ponderous Leptccna is nearest to L. vcntri- 

 cosa, a contemporaneous form in the Appalachian trough, but is 

 larger and readily distinguished by its contour and the subdued 

 character of its corrugations. Externally it resembles some of 

 the large Leptostrophias rather than a Lcptcena, but the deep 

 ventral muscle-scar is distinctly that of the latter genus. 



Occurrence: Harriman novaculite, near Camden, Parsons, 

 Perrvville, etc. 



Pholidostrophia lindenensis, n. sp. 



Plate II, figs. 15, 16 



Description: Shell small, semi-elliptical in outline, hinge-line 

 a little longer than the shell in front of it. Ventral valve 

 strongly and evenly arched, almost hemispherical, with the curva- 

 ture slightly flattened only near the cardinal extremities. Con- 

 tour of the dorsal valve closely conforming to that of the ventral. 

 Hinge-line denticulate. Surface entirely smooth. Inner layers 

 of the shell coarsely punctate. 



Dimensions: Length, 9 mm.; width, 12 mm.; depth of con- 

 vexity, 4.5 mm. 



Discussion: In its size and contour this little shell resembles 

 P. {f) niagarensis of the mid-Silurian, but that species shows 

 distinct striations and has a more gibbous umbonal region. 

 From P. iozvaensis of the Middle Devonian it difl:'ers in being 

 more strongly arched, proportionately longer and narrower, and 

 in the absence of lamellose growth varices. 



Occurrence: A rare shell in the Birdsong shale, found at 

 Perry ville and at the old Swayne's mill site near the mouth of 

 Big Sandy River. 



Brachyprion purduei, n. sp. 

 Plate II, figs. 22, 23 

 Description: Shell semi-elliptical, length generally about three- 

 fourths the width but in some cases equalling the latter. \'en- 

 tral valve evenly and rather strongly convex, the greatest ele- 

 vation being near the center, from which point there is an equal 

 curvature to the anterior, posterior, and lateral margins. Hinge- 

 line straight and equalling or slightly exceeding the width of the 



