263 



Found in the Enci-inal limestone, at Section 5 (several 

 fragments, probably of this species, thongh the characters 

 are very much obliterated). 



CoxocARDiUM CRASSIFKONS. ( C o n V ad.) 

 (Fig. 182 A.) {Pleurorhynchus crassi&ons. 

 Conrad: Jonrn. Acad. Nat. Sci. Phil., Vol. 

 Till., Pt. I., p. 252, PI. XIII., 1.S89.) 



DLstinguishing' Charncters. — Small size; 

 short valves; broad truncated anterior end; 

 narrow posterior (winged) end; elevated 

 distant beaks; five or six convex radiating 

 lines on each valve. 



Found in the Hamilton group of Eighteen '^;'^"lZ\tn(eZr\b^'s 

 MileCreek. (Am. Mus.Xat. Hist. New York.) ^afterSit/'^ ^'^^'i 



Fig. 182A. Conocar- 



Genus LUNULICARDIUM. Munstek. 



[Ety. : Lunuld, a little moon; cardium, a genus.] 

 (1840: Beitrage zur Petrefactenkunde, 3tes Heft., s. 69.) 



Shells with equal inequilateral valves, transversely sub- 

 elliptical, sub-circular, or trigonal in outline. From the 

 terminal beaks a sharp angular ridge runs downward, 

 delimiting a flattened, heart-sha])ed anterior area or lunule, 

 ^vhich has a central byssal opening. Surface marked b}' con- 

 centric striae, and often by strong radii. 



LUNULICARDIUM FRAGILE. Hall. (Fig. 183.) ( Pal. N. Y., 

 Vol. v., Pt. I., p. 434, PI. LXXl.) 



Distinguishing Characters. — Small size; fragile condition; 

 smooth surface, which shows only fine concentric lines, and 

 rarely very fine radiating lines; lunule with a thin expansion 



Fig. 183. Lunulicardium fragile. Four specimens, illustrating variations, enlarged 

 X 2 (from Hall). 



