LAMELLIBRANCHIATA. 387 



Edmondia Philipi. 



PLATE LXIV, FIGS. 9, 11-14, 17, 29; and PLATE XCV, FIGS. 1-4. 



In part Edvumdia Philipi, Hall. Prelim. Notice Lamellibranchiata, 2, p. 90. 1870 



" " " " Pal- N. Y., vol. V, pt. 1. Plates and Explanations : PI. 64, tigs. 9-18. 



1883. 

 Biirlingtonensis (White and Wihtfibld), Hall. Prelim. Notice Lamellibranchiata, 2, p. 



90. 1870. 

 Pal. N.Y., vol. V, pt. 1. Plates and Ex- 

 planations : PI. 64, figs. 19-29. 1883. 



Shell of medium size or larger, very broadly elliptical ; length greater than the 

 height. Pallial margin regularly curving from the extremities. Posterior 

 margin sometimes sub-truncate. Cardinal line straight or gently curving. 

 Anterior end broad and regularly rounded. 



Valves moderately convex in the lower and posterior part, becoming gib- 

 bous in the middle and above. 



Beaks sub-central. Umbonal slope convex, not defined. 



Test thin. Surface marked by fine, closely arranged, concentric striae, 

 which are sometimes raised into slender, lamellose expansions. Specimens 

 in the sandstones often show obscure, broad plications along the pallial mar- 

 gin which do not extend above the middle of the valve, and are not external 

 features of the shell. Interior unknown. 



Three specimens measure respectively 29, 32 and 44 mm. in length, and 

 24, 25 and 38 mm. in height. 



This species, in some of its smaller individuals, closely resembles the pre- 

 ceding. 



The general form of the shell in the shales is broadly sub-oval, approaching 

 sub-circular ; the surface is finely striated concentrically with some gentle 

 undulations of the shell. 



The sharp, distant, elevated, lamelliform striae which mark the surface of 

 some specimens are due to the condition of preservation, the finer striae having 

 been obliterated. 



Formation and localities. In the shales of the Chemung group, at Philipsburgh 

 and Kockville, in the sandstones at Hobbieville, Randolph and Connewango, 

 N. Y., and in the shales and sandstones at Mansfield, Pa. 



