LAMELLIBRAN CHI A TA. 
379 
length, abruptly recurving at the post-basal extremity and obliquely truncate 
above. Cardinal line nearly straight, scarcely declining posteriorly. Ante¬ 
rior end short, obliquely truncate above, at the lunule, and abruptly rounded 
below, having an angle at the junction of the two lines. 
Valves regularly convex in the lower and posterior portions, becoming 
gibbons above and especially on the post-umbonal slope. 
Beaks sub-anterior, prominent, large, strongly incurved. Umbonal slope 
obtusely sub-angular, and extending to the posterior extremity, with a faint 
indication of a plication on the post-cardinal slope. Valves marked by a 
distinct cincture extending from the beak, more or less obliquely, to the 
basal margin anterior to the middle of its length. 
Surface marked by fine concentric striae, which are obscurely visible in 
the cast; and by strong concentric undulations which mark the anterior and 
central portion of the valves, becoming obsolete on the umbonal ridge. Inte¬ 
rior unknown. 
Five specimens measure respectively 29, 30, 32, 35 and 44 mm. in length, 
and 47, 17, 21, 17 and 24 mm. in height. 
This shell has been identified as Grammysia (Allorisma) Hannibalensis, of 
Shumard, but compared with authentic examples of that species from the 
original locality it is found to differ in its more elongate form, sub-angular 
umbonal slope, more oblique cincture, and more strongly defined concentric 
folds. 
Formation and localities. In the Chemung group, at New Albion, Olean, Port- 
ville, and Little Genesee, N. Y. ; and at Warren, Pa. 
Grammysia undata. 
PLATE LXI, FIG. 23; PLATE LXIV, FIG. 30; AND PLATE XCIII, FIG. 21. 
Edinnniia nndata, Hall. Pal. N. Y., vol. v, pt. 1. Plates and. Explanations: PI. G4, fig-. 30. 1883. 
Shell below the medium size; ovate sub-elliptical; length about one-third 
greater than the height; basal margin gently curving, nearly straight, and 
slightly constricted anterior to the middle of its length. Posterior margin 
