LAMELLIBRANCHIA TA. 
45 
smaller intermediate implanted rays, crossed by fine, regular, elevated sharp 
lines of growth, which at intervals are raised into lamellae, and appear in the 
cast as strong transverse ridges crossing the radii. The furrows between the 
radii are narrower than the rays. The regular alternation of the radiating 
lines where seen is a very conspicuous feature. The right valve is marked 
by more numerous and subdued rays, and their alternation is somewhat 
obscure. The ears show fine radiating lines and stronger and more crowded 
concentric striae. 
The differences between the right and left valves, are the convexity, the 
surface markings, and the deep byssal sinus of the right valve. 
The characters of the interior are not known. 
A medium-sized individual has a height of 47 mm., longitudinal diameter 
54 mm., hinge-line 32 mm. A smaller specimen measures in height 35 mm., 
length 38 mm., hinge-line 24 mm. 
The largest specimen (imperfect) shows a height of 74 mm., and a length 
of 88 mm. 
In outline and general aspect this species closely resembles L. macrodontus 
(plate 8, figs. 9, 10), but differs in the obliquity of the beak, wider anterior 
ears, and more elevated and numerous rays. It differs from L. magnificus in 
its outline, larger anterior ears, longer liinge-line, and finer radii of the ears. 
The anterior ears of this species, and also of L. solox and L. polydorus, are 
smaller than in the species referred to Aviculopecten. 
The specimens mostly preserve both valves in connection. A large specimen 
(plate 82, fig. 5), occurring in the harder argillaceous sandstone, attains nearly 
the dimensions of L. cymbalon (plate 24, fig. 8), but differs conspicuously in the 
more numerous, strong radii, their gentle curvature toward the anterior side, 
and the smaller area of surface upon the anterior side of the vertical axis of 
the valve. 
Formation and locality. In the shales of the Hamilton group, Fultonham, 
Schoharie county, N. Y. 
