i'i;:: 



Found in the EncrinaJ limestone, at Section ."> (several 

 fragments, probably of this species, though the characters 

 are very much obliterated). 



( JONOCABDIUM CRASSIFRONS. ( ( ' ( ) 11 r ;l (1 . ) 



(Fig. 182A.) (Pleurorhynchus crassifrons. 

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

 YIIL, Pt. I., p. 252, PL XIII., 1839.) 



Distinguishing Characters. — Small size; 

 short valves; broad truncated anterior end; 

 narrow posterior (winged) end; elevated 

 distant beaks; five or six convex radiating 

 lines on each valve. 



Fig. 182A. Conocar- 



Found in the Hamilton group of Eighteen SSiSaSSS^J^ 

 Mile Creek. (Am. Mus. Nat. Hist. New York.) gL*i oSSSSSBS" *'"'" 



Genus LUNULICARDIUM. Munster. 



[Ety. : Lunula, 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-shaped anterior area or lunule, 

 which has a central byssal opening. Surface marked by con- 

 centric stria?, and often by strong radii. 



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

 Vol. Y, Pt. I., p. 434, PL LXXI.) 



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, enlawl 

 x 2 (from Hall). 



