411 Modi. 



of New York, but of larger dimensions; fig. 6, right valve, 

 having a proportionally greater length ; in this feature more 

 nearly approaching the New York species. Glinton and Niag- 

 ara.— ^ee ^i^eQimen^ 501-19^, 40, 46-50, in Hale and Hall's 

 collections at the McKee fossil ore bank, Mifflin Co., Pa. (00, 

 p. 233); Spec. 502-9 (nine examples); 502-16J; 502-21; same 

 outcrop, roof shale of ore bed ; 504-42 from Bell's Mills ; and 

 508-16 in Hall and Fellows' coll. at Orbisonia, also in CUfiton 

 shale. — Va. Vh. 



Modiolopsis subcarinata, Hall, Pal. N. Y., Vol. 2, 1852, 

 Clinton. Found by C. E. Hall in Ferguson Valley, Mifflin Co., 

 Pa., in Clinto?i^ — Va. See Appendix. 



Modiolopsis subrhomboidea, N. S. Simpson, Trans. A. 



va. ^'— vr--^ P. S., Phila., 1889, page 450, fig. 17; 



; ;. '' . \ founded on specimens 501-47 of Hale and 

 y ^, Hall's collections at McKee's ore bank. 



; y Shell of medium size, rhomboid ovate in 



APS ^'"^^"'~"-— ^— frfsag outline; length twice the height; basal 



margin slightly convex along the middle, curving to the ex- 

 tremities; posterior margin abruptly rounded below, somewhat 

 more gradually recurving to the cardinal line ; cardinal margin 

 slightly arcuate; anterior margiin sharply rounded. Valves 

 flattened, greatest convexity at the umbonal ridge. Hinge 

 line slightly oblique, extending a little more than two-thirds 

 the length of the shell. Beaks appressed, situated about one- 

 fourth the length of the shell from the anterior end; umbonal 

 ridge not distinctly defined; posterior slope rounded, becoming 

 flattened just before reaching the cardinal line. Surface marked 

 by fine concentric lines, and at irregular distances apart by 

 varices of growth. The anterior muscular impression is mod- 

 erately large, well marked, and situated just within the ante- 

 terior margin below the beak. The best preserved specimen 

 has a length of 24 mm., and a height of 13 mm. This species 

 may be distinguished from M. subcarinatus by the less clearly 

 defined umbonal ridge, the somewhat arcuate hinge line, and 

 absence of a constriction in the basal margin. Formation and 

 locality. Clinton shale, above fossil ore, at McKee's ore bank, 

 north-east of McKee's house, Ferguson valley, seven miles 

 north-west of Lewistown, Mifflin county, Pennsylvania. — Va. 



