LINGULJE OF THE HAMILTON GROUP. 
S> 
Lingula leana (n. s.). 
PLATE II. 
Shell robust, ovate, subattenuate towards the beak; margins gradually 
expanding and curving from the beak for about two-thirds the length, 
where the shell has its greatest width. Lower half of the shell very 
depressed-convex, becoming more convex towards the beak. Shell 
comparatively thick, lamellose. 
Surface marked by fine concentric strise and faint interrupted radiating 
striae, which are more conspicuous and continuous in the exfoliated 
shell. The length of an apparently full grown individual is eight-tenths 
of an inch, and the greatest width eleven-twentieths of an inch. 
This species is conspicuously distinct from any others in the Hamilton and 
Chemung groups, except L. palceformis , from which it differs in its greater propor¬ 
tional length and more attenuate form towards the beak. So far as known to me, it 
is a rare species. 
Geological formation and locality. In some calcareous layers in the Hamilton 
shales, in Bristol, Ontario county, N.Y. 
Lingula maida (n. s.). 
PLATE II. 
Shell linguiform, elliptical, greatest width a little more than half the 
length, narrowing gently towards either extremity, obtusely rounded 
and produced below, and more acutely converging towards the beaks. 
Surface very gently convex below and a little more convex on the umbo, 
marked by fine threadlike strise which are sometimes crowded in fa¬ 
scicles. No radiating strise are preserved in the specimen. 
The specimen described is apparently a ventral valve, and preserves some remains 
of the muscular impression. In form it resembles the L. ligea , but is less convex, 
and the lower part of the shell is more produced, so that the strise make a more 
extended curve than on that species; and they are likewise coarser. 
The typical forms of L. ligea are about half an inch in' length and one quarter of 
an inch in width; and the L. maida has a length of more than three-fourths of an 
inch, with a width of nearly half an inch. 
Geological formation and locality. In the Moscow shales of the Hamilton group: 
at Moscow, N.Y. 
[ Paleontology IV.] 2 
