LAMELLIBRANCHIATA. 507 



Gbammtsia? subnasuta. 



PLATE LXIV, FIGS. 5, 6. 

 Edmondia xtUmasuta, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 64, figs. 5, 6. 1883. 



Shell somewhat below the medium size, narrowly ovate or trapezoidal in out- 

 line ; length more than one-third greater than the height ; basal margin regu- 

 larly curving from the post-inferior angle to the middle of the anterior end. 

 Posterior extremity obliquely sub-truncate. Cardinal line nearly straight, 

 gently declining posteriorly from the beaks. Anterior end narrowly rounded. 



Left valve regularly convex below, becoming gibbous in the middle and 

 umbonal region. 



Beaks at about the anterior third, prominent and rising above the hinge- 

 line. Umbonal slope not distinctly defined, gibbous and extending to the 

 post-inferior extremity, producing a sub-nasute extension. 



Surface of the cast marked by fine concentric striae, and at the anterior 

 end there are some remains of concentric ridges which are obscurely visible 

 in the cast of the body of the shell. Interior unknown. 



A specimen of normal proportions has a length of 35 mm. and a height of 

 20 mm. 



This species may be compared with G. glabra, but it is a much narrower 

 form, with a proportionally longer hinge-line and more pointed and truncate 

 posterior extremity. The shell is clearly not related to Edmondia, but its 

 generic relations are more nearly with Grammysia. 



Formation and locality. In the coarse sandstone or conglomerate of the 

 Chemung group, at Portville, N. Y. 



