Weller — Kinderhook Faunal Studies. 69 



edly the little shell here described that he had in mind, be- 

 cause of its abundance at Burlington in the Chonopectus 

 sandstone, and especially in the thin limestone band which lies 

 just above the sandstone. This limestone band which is only 

 a few inches in thickness is usually constituted almost wholly 

 of the shells of this single species. Upon the internal casts 

 of the pedicle valve in the Chonopectus sandstone, such as the 

 one here illustrated, the radiating striae can usually not be 

 recognized, hence their absence from the figure. 



Chonetes sp. undet. 



PL I. f. 15. 



A few imperfect specimens of a third species of Chonetes, 

 not yet identified with any described form and intermediate 

 in size between the other two, have been found in the Chono- 

 pectus sandstone. It differs from either of its associates in 

 its coarser radiating striae, there being only 40-50 on each 

 valve. The shell is also much more extended along the hinge- 

 line, the cardinal extremities being acutely angular. The 

 species somewhat resembles C, ovnatus from the Louisiana 

 limestone at Louisiana, Missouri, but the striae are finer and 

 the cardinal extremities more acute than in that species. The 

 best specimen observed is an impression of the outside of the 

 brachial valve which is moderately convex in the middle and 

 flattened towards the cardinal extremities. The contour of 

 the pedicle valve is not certainly known. 



Chonopectus fischeri (N. & P.). 



PI. I. f. 17. 



Shell semi-elliptical in outline, the hinge-line equal to or a 

 little less than the width of a shell. Pedicle valve convex, 

 somewhat gibbous in the middle, often nearly flat at the umbo 

 and along the hinge-line, compressed at the cardinal angles; 

 the hinge-line furnished with five to seven nearly straight tub- 

 ular spines on each side of the beak, those nearest the beak 

 usually being at right angles to the hinge-line while the outer 

 ones are slightly oblique. Brachial valve moderately concave, 

 following the curvature of the opposite valve. Surface marked 

 by fine radiating striae, by concentric lines or wrinkles of 



