390 The American Geologist. June, 1892 



Agnostus canadensis Billings, 1860. Plate ix, fig. 9. 



Dlag)iosis. — 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 obtusel}^ 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. 



Tjocality. Point Levis, Quebec. 



Agnostus communis Hall and Whitfield, 1877. Plate ix, fig. 15. 



Diagnosis. — Head subparaboloid, wider than long. Surface 

 strongly convex. Glabella nearly equaling ^ of the width of the 

 head ; anterior third separated from the posterior lobe by a faint, 

 transverse furrow. Central part of the glabella ornamented bj^ 

 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. A.n 

 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 cyclo'pyge Tullberg. 



Agnostus coloradensis Shumard, 1861. Plate ix, fig. 16. 

 • The description was drawn from a single example found in 

 Burnet county, Texas, near the mouth of Morgan's creek; the 



