LAMELLIBRANCHIA TA. 
469 
ciculate on the anterior and posterior extremities. The striae recurve over 
the umbonal ridge, at a slightly acute angle. 
The specimens are casts of the interior in sandstone, and the surface 
markings are not well preserved. Anterior muscular impression large, not 
deep, situated just within the margin below the lunule. 
A specimen has a length of 82 mm. and a height of 30 mm. 
This species resembles C. recurva, but differs in the strong angular umbonal 
ridge, which extends to the post-inferior extremity, and by the sharp recurv¬ 
ing of the striae over this ridge. 
Formation and localities. In the Chemnng group at Chemung Narrows, and 
between Elmira and Waverly, Tioga county, N. Y. 
PHOLADELLA, Hall. 1870. 
PlIOLADELLA RADIATA. 
PLATE LXXVIII, FIGS. 15-21 ; and PLATE XCVI, FIG. 1. 
Nuculites radiata, Conrad. Jour. Acad. Nat. Sci., Phila., vol. viii, p. 24S, pi. 12, fig-. 16. 1842. 
Pltoladella radiata (Conrad), Hall. Prelim. Notice Lamellibranchiata, 2, p. 63. 1S70. 
“ “ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PL 78, figs. 
15-20. 1883. 
“ truncata, Hall. Prelim. Notice Lamellibranchiata, 2, p. 64. 1870. 
“ ornata , “ Prelim. Notice Lamellibranchiata, 2, p. 64. 1870. 
Shell from small to medium size, elongate-ovate, cuneate; length about twice 
the height. Basal margin regularly rounded, curving in a greater or less 
degree according to the age of the individual. Posterior extremity more or 
less obliquely, or sometimes vertically, truncate. Cardinal line straight, 
sometimes a little concave. Anterior end short, obliquely truncated by the 
lunnle and narrowly rounded below. Escutcheon large and well-defined. 
Lunule deep, marked by an abrupt incurving of the margin. 
Valves, in their usual condition of preservation, moderately convex below 
and gibbous in the middle. In a well-preserved specimen the valves are 
very gibbous, the depth of both valves being equal to the height of the shell. 
Beaks sub-anterior, prominent, strongly incurved. Cincture extending 
60 
