257 



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

 thread-like striae, which become obsolete in the furrow and 

 on the post-cardinal slojie. 



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

 shale below at three feet and twenty-one feet below the 

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

 above the Pleurodictvum beds, in Avery's Ravine. 



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

 N. Y., Vol. v., Pt. I., p. 336, Pis. XLIX., XCIIl.) 



Distinguishing Ch a racte rs. — vate elliptical outline ; 

 doubly-truncate posterior end ; slight depression extending 



.<i*^P^^ 



Fig. 174. Palceoneilo tenuistriata. A specimen retaining both valves : a riglit 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 strife, often crowded on the posterior portion of the 

 sheU. 



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, at Sections 5 to 8; and in the Strophalosia bed. on the 

 Lake Shore (where it is very rare). 



Pal^oneilo fecuxda. Hall. (Fig. 175.) (Pal. N. Y., 

 Vol. v., Pt. L, p. 33G, PI. XLIX.) 



Distinguishing Characters. — Elongate ovate outline; 

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

 truncate, posterior margin ; fine concentric stride, which 

 become elevated into sharp lamelhe, alternating in size on 

 the posterior slopes. 



