anterior portion of cardinal margin; fine, regular and even, 

 thread-like stria?, which become obsolete in the furrow and 

 on the post-cardinal slope. 



Found in the Demissa bed, at Section 5 (rare) ; and in I he 

 shale below at three feet and twenty-one feet Ik 'low the 

 Encrinal limestone, at Section 7 (rare); also in the shale 

 above the Pleurodictyum beds, in Avery's Ravine 



Pal^eoneilo tenuistriata. Hall. (Fig. 174.) (Pal. 

 N. Y., Vol. V., Pt. I., p. 336, Pis. XLIX, XCIII.) 



Distinguishing Characters. — Ovate elliptical outline; 

 doubly-truncate posterior end ; slight depression extending 



Fig. 174. Palceoneilo tenuistriata. A specimen retaining both valves ; a right valve 

 (from Hall). 



from posterior to the beak, to the post-inferior margin, where 

 it causes a slight constriction in the margin; very fine con- 

 centric striae, often crowded on the posterior portion of the 

 shell. 



Found in the lower Moscow shale, at Sections 4 and 5 ; in 

 the Lower shale, down to and in the shale below the Trilobite 

 beds, a,t Sections 5 to 8; and in the Strophalosia bed, on the 

 Lake Shore (where it is very rare). 



Palceoneilo fecunda. Hall. (Fig. 175.) (Pal. X. Y., 

 Vol. V., Pt. I., p. 336, PL XLIX.) 



Distinguishing Characters— Elongate ovate outline; 

 length nearly twice the height; obtusely rounded, or doubly- 

 truncate, posterior margin; fine concentric striae, which 

 become elevated into sharp lamella?, alternating in size on 

 the posterior slopes. 



