40 
PALEONTOLOGY OP NEW-YORK. 
Surface marked by even rounded striae, which, at intervals, show small 
tubular openings, while the intermediate space is minutely papillose or 
punctate according to the condition of the surface. 
The specimen described has been a little compressed, but it appears to have 
possessed a broad shallow sinus on the ventral valve, very similar to 0: oblata 
of the Lower Helderberg group : the striae are stronger and more rounded than 
in that species. 
The length of this specimen is nearly six-eighths of an inch, and its width 
seven-eighths of an inch; but it is probably not an adult individual, and, without 
more material, I hesitate to characterize it, since it belongs to a group of Orthides 
of which there are numerous closely allied species. 
Geological formation and locality. In the Corniferous limestone of Western 
New-York. 
Orthis vaimxemi? 
PLATE Y. 
Orthis vanuxemi, Hall. See the same under Hamilton group. 
A single specimen of a ventral valve, from the limestone, possesses 
characters undistinguishable from those of 0. vanuxemi. This specimen, 
however, is the only one of the species which has come under my ob¬ 
servation from the limestone. Numerous imperfect casts and exfoliated 
shells bear close resemblance to the species, and may prove to .belong to 
the same. 
Geological formation and locality. In the limestone of the Upper Helderberg 
group, near Caledonia, Livingston county, N.Y. 
Orthis semele (n. s.). 
PLATE V. 
Some imperfect specimens showing the interior of the ventral valve, 
and also a small specimen of the ventral valve, possess characters ap¬ 
proaching very nearly to 0. vanuxemi. From the same locality there have 
been obtained casts of a dorsal valve, which are more elevated in the 
