LINGULJE OF THE UPPER HELDERBERG ROCKS. 
5 
&Jenus Lingula (Bruguiere). 
Up to the time of commencing the printing of this volume, I do not 
know of more than a single species of Lingula in the Schoharie grit, 
and but two in the Upper Helderberg limestone. 
' Several species occur in the limestones of the Lower Helderberg group, 
and which have been already described; but none are known to occur 
in the Oriskany sandstone, and but three species between that rock and 
the Marcellus shale or base of the Hamilton group. Collections of con¬ 
siderable extent have been made, and Qver a large area of country; and 
judging from these, the shells of this genus were extremely rare in the 
early epochs of the Devonian period in this country, ^he species are for 
the most part rare in the Hamilton group, so far as my examinatons have 
extended, and one only is known to be abundant. 
LINGULAE OF THE UPPER HELDERBERG GROUP. 
Lingula ceryx (n. s.). 
PLATE II. 
A single specimen has been obtained, three-fourths of an inch in length 
by half an inch in breadth. Yery little of the shell is preserved; merely 
sufficient to show that it was marked by fine concentric striae, with the 
cardinal margin thickened. The cast has a distinct oval impression a 
little above the centre, showing the mark of a muscular callosity at that 
point. 
This species resembles in form the L. densa of the Hamilton group, but has not 
the strong radiating striae of that species, while the subcentral muscular callosity 
is also different. 
Except that this is the only representative of the genus known to me in the 
Schoharie grit, I would not have thought it worth while to designate the species 
from a single imperfect specimen. 
Geological formation and locality. In the Schoharie grit : near Clarksville, 
Albany county, New-York. 
