214 SW. Ford—Primordial fossils of Rensselaer Co., N. Y. 
along the line of the longer axis of the shell. The slope of the 
shell is unequal, being most rapid toward the margin to which 
the apex inclines. The surface is marke 
by a few fine concentric and radiating lines, a x b 
the latter only visible under a magnifier, and 
with obscure imbricating lines of growth. ,. ._ wua retuan: a 
Length of the largest specimen obtained, gide. view a upper view. 
0-16 of an inch; height about 0-08 of an 
inch. Occurs in both even-bedded and conglomerate limestone 
of the Potsdam group at Troy, associated with the preceding 
species. Collected by the writer. 
This species is closely related to Scenella reticulata, the only 
hitherto published species of the genus, described by Mr. Bil- 
lings in the Canadian Naturalist for July last from the Mene- 
vian group of Newfoundland. That species is, however, con- 
siderably larger than ours; and is, further, destitute of the 
diverging grooves which exist in S. retusa, and by which this 
latter species may be easily recognized. 
Hyolithes Emmonsi, sp. nov. 
Shell elongate, slender ; apex neatly pointed, transverse sec- 
tion sub-triangular. Sides gently rounded and meeting to form 
a tolerably prominent though often scarcely perceptible dorsal 
ridge in the forward part of the shell, which quickly dies down, 
so that a transverse section taken near the apex would be almost 
asemi-circle. Ventral side flattened, with a wide, shallow depres- 
sion along the middle, which runs the whole length of the shell; 
lateral edges rounded up to the sides. The most projecting 
Fig. 3.—Hyolithes Emmonsi ; a, ventral view of an imperfectly terminated speci- 
men; 8, transverse section; c, operculum, enlarged two diameters. 
point of the lateral walls occurs close to the ventral side. When 
the width is 0-24 of an inch the depth is 0°18 of an inch. The 
walls of the shell are thick and appear to be made up in some 
instances of successive layers or lamin. The surface is orna- 
mented with very fine concentric striae, which run directly 
around the shell or at right angles to its longitudinal axis. 
e tubes sometimes attain a length of two inches, even when 
imperfect ; but the majority of the specimens in my possession 
are less than an inch in length. : 
The operculum has the same contour as a transverse section 
of the shell taken at about the mid-length, and is, accordingly, 
distinctly emarginate at the middle of the border of the ven 
limb. e ventral limb itself is in the main flat, or nearly 50 
and embraces not far from two-thirds of the whole superfices of 
