390 The American Geologist. Tune, 1892 
AGNOSTUS CANADENSIS Billings, 1860. Plate 1x, fig. 9. 
Diagnosis. —Head obtusely oblong, semi-oval, width a little 
greater than the length, a concave border nearly as wide as the 
glabella all around. Glabella in width less than $ the width of 
the head, and in length a little more than $ the length of the head. 
Basal lobes small. The transverse furrow marking the frontal 
lobe of the glabella is located a little in advance of the mid- 
length; the tubercle is obscure and appears to be indicated by the 
small indentation in the middle of the transverse furrow. The 
cheeks are separated in front of the glabella by a furrow. 
The author doubtfully figures a pygidium of this species. It 
has a similar form to that of the head of A. canadensis with the 
concave border all around the margin. The axis is obtusely cla- 
vate, and marked with two joints. The posterior joint is large 
and convex, extending quite to the concave border, where it is 
full half as wide as at the furrow which divides the two joints, 
The tubercle is situated in the transverse furrow and makes a 
small indentation in the edge of the posterior joint. 
Local:ty. Point Levis, Quebec. 
Aanostus communis Hall and Whitfield, 1877. Plate 1x, fig. 15. 
Diagnosis.—Head subparaboloid, wider than long. Surface 
strongly convex. Glabella nearly equaling 4 of the width of the 
head; anterior third separated from the posterior lobe by a faint, 
transverse furrow. Central part of the glabella ornamented by 
an elongated and angular tubercle. Dorsal furrow distinct. 
Cheeks separated in front of the glabella by a groove. Basal 
lobes triangular. Limb flattened. Thorax unknown, 
The pygidium with a flattened limb, which is ornamented with 
lateral spines. Surface strongly convex; in the anterior half, the 
dorsal furrow being directed gently inward for half their length, 
and then suddenly deflected outward, with a slight curvature, be- 
coming obsolete a little behind the middle of the length. An 
elongated angular node marks the axis near its anterior margin. 
Surface of the head and pygidium smooth. 
Locality. White Pine, Nevada. 
This species is of the type Agnostus cyclopyge Tullberg. 
AGNOSTUS COLORADENSIS Shumard, 1861. Plate 1x, fig. 16. 
The description was drawn from a single example found in 
Burnet county, Texas, near the mouth of Morgan’s creek; the 
