318 
Aug. F. Foerste 
iferous/’ Moreover, Green himself, in his Monograph of North 
American Trilobites, states: “Mr. Eaton says that Nuttainia 
concentrica ^occurs in the wacke variety of transition of argilites on 
the Champlain canal, ^ between the town of Waterford and the 
Mohawk river. The specimen in my cabinet, from which our 
cast was made, is from that place. 
The rather meager fauna so far discovered at Waterford has 
been found, by Dr. Rudolf Ruedemann, to belong stratigraph- 
ically to the Snake Hill beds, which at the type locality, on the 
east side of Saratoga Lake, contain a much larger fauna, placed 
by Dr. Ruedemann near the base of the Trenton, below the Cana- 
joharie shale. 
It is scarcely likely that the Trinucleus found in the Pulaski 
division of the Lorraine belongs to the same species as this Snake 
Hill form, but no material is at hand hy means of which the two 
forms may be discriminated. 
The following is a description of a series of specimens occurring 
in a single block of finegrained Lorraine rock from which most of 
the lime had been dissolved, leaving the specimens in the form of 
of casts of the upper and lower surfaces of the cephalon. 
Glabella obovate, tumid in front, becoming lower and narrower 
posteriorly; at the posterior margin of the cephalon its width is 
equal to half, or slightly less than half the width of the glabella 
anteriorly. Here the posterior end of the glabella is crossed by 
the nuchal furrow in a direction convex to the rear, posterior to 
which the glabella extends with a rounded V-shaped outline, pro- 
jecting behind the posterior margin of the cephalon a distance 
about equal to the width of the glabella at this margin. Pos- 
teriorly, this nuchal V-shaped segment of the glabella terminates 
in a sharp narrow spine about 2 mm. in length, always present, 
but generally overlooked. On each side of the posterior part of 
the glabella, in the nuchal groove, and also a very short distance 
anteriorly, there is a small depression or pit which is the only evi- 
dence of segmentation shown by the glabella. The glabella rises 
an amount equal to almost half its width above the general con- 
vexity of the cheeks. The latter are moderately convex over most 
of their surface, becoming slightly tumid only laterally, where 
they adjoin the pitted border. A narrow groove separates the 
cheeks from the equally narrow raised posterior border of the 
cephalon. For two-thirds the width of the cheek, the posterior 
