FOSSILS OF THE CARBONIFEROUS. 235 
Genus PTYCHOPTERIA Hall. 
Ptychopteria protoforme, n. sp. 
Plate viii, fig. 5. 
Shell obliquely elongate, narrowing anteriorly; posterior ear broad 
and straight, anterior ear short; beak anterior, obtusely rounded; hinge 
line long, but not quite equaling the greatest width of the shell below. 
Surface marked by obscure lines of growth. 
Interior characters unknown. 
‘Dimensions: height, 12"; greatest breadth, 20"; convexity of left 
valve, 2™™ to 3™™. 
The outline of this species is more nearly like that of Ptychopteria 
Proto Hall (Pal. N. Y., vol.-y, pt. 1, p. 129, 1884) than that of any other 
species known to me. ‘The ear is not as broad, and it also terminates in a 
more acute angle with the hinye-line, in this respect resembling P. sinuosa 
Hall (loc. cit. p. 130). 
Formation and locality—Lower portion of Lower Carboniferous lime- 
stone on east slope of a small conical hill on the east side of Secret-caiion- 
road Canon, Eureka District, Nevada. 
Genus PINNA Linneus. 
Pinna inexpectans, n. sp. 
Plate xix, fig. 11. 
Shell elongate, lanceolate, over four times longer than wide; section 
elliptical, valves not very convex; ventral and dorsal margins straight or 
slightly convex. -The dorsal or cardinal margin is a little thickened and 
with a well-defined rounded rim at the edge. 
Surface marked by strong ridges subparallel to the dorsal and ventral 
margins; they are more or less flexuous, and while obsolete on the upper 
portion of some examples, are present on the entire width of the shell in 
others. A few obscure concentric lines, parallel to the posterior margin, 
cross the radiating plications. 
