304 NEW YORK STATE MUSEUM 



relation to the sculpture ribs, but this observation was made on Siluric 



shells, and we have been able to find no corresponding structure in the 



delicate barite replacements derived from the Naples beds. These shells 



are of diminutive size, and such cardinal features as they possess are very 



obscure. 



Paracardium doris Hall 



Plate 11, fig. 5-10 



Cardiol a doris Hall, Paleontology of New York. 1883. v. 5, pt 1, plates and 



explanations, pi. 70, fig. 10, 11 

 Paracardium doris Hall, Paleontology of New York. 1885. v. 5, pt 1, p. 428, 



pi. 70, fig. 10, 1 1 



Shell very small, subcircular in outline when uncompressed, but usually 

 somewhat elongate transversely or obliquely. Beaks minute, incurved and 

 directed forward, umbones full and convex, the general contour of the shell 

 being rotund and regular. Hinge line quite short and but slightly inter- 

 rupting the regularity of the periphery. Surface covered with 20 to 25 fine 

 rounded ribs, separated by narrower furrows. Occasionally these ribs 

 show very faint traces of concentric lines. The shell rarely has a length 

 and breadth exceeding 4 mm. 



Habitat. Genesee province ; Naples subprovince. Common in the 

 Styliola limestone in Ontario county and in the lower, soft shales of the 

 Naples beds in Yates, Ontario, Livingston and Genesee counties; in the 

 Wiscoy shale, Wiscoy creek, Allegany co.; it is rare farther west and has 

 not been seen in Erie and Chautauqua counties. The species also occurs 

 at Folks Mill and other localities in Allegany county, Md. 



Paracardium delicatulum sp. now 



Plate 11, fig. 4 



Shell of about the same size as Parac. doris, beak nearly median, 

 outline transversely subcircular, extended slightly on the posterior margin. 

 Surface convex, the greatest elevation being along a median line from 

 the beak to the ventral margin. The ornamentation consists of a great 

 number, 60 or more, of fine, filiform radiating lines. 



Habitat. Genesee province ; Naples subprovince. This is a rare 



