LAMELLIBRANCHIA TA. 
413 
angle to the anterior end are very strong and elevated, obscuring the radii. 
Interior unknown. 
All the specimens known are much distorted by pressure, and the entire 
characters cannot be determined. 
One specimen has a length of 19 mm. and a height of 9 mm. A large 
specimen measures 25 mm. in length. 
Formation and locality. In the shales of the Hamilton group, at York, Living¬ 
ston county, N. Y. 
CONOCARDIUM DENTICULATUM. 
PLATE J,XVIII, FIGS. 24, 25. 
Conocardium denticulatnm, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PL 68, tigs. 24, 25. 
1883. 
Shell small, ovate-cuneate; basal margin straight. Body gibbous, truncate 
behind, abruptly contracted and attenuate in front. 
Body of the shell marked by five or six strong angular radii; those of the 
post-cardinal slope unknown. The anterior end is cancellated by fine radii 
and lamellose concentric striae. The interspaces between the strong radii 
are marked by fine concentric striae. Anterior portion of the shell gaping, 
the margins of the valves furnished with distant lamelliform denticulations. 
Interior unknown. 
The fragment described has a length of 10 mm. and a height of about 5 mm. 
This form differs from C. Eboraceum in the strong angular radii upon the 
body of the shell; the post-cardinal area is smaller and the anterior portion 
more contracted and attenuate, with much finer radiating and concentric striae. 
Formation and locality. In the shales of the Hamilton group, at York, Liv¬ 
ingston county, N. Y. 
53 
