26 PALEONTOLOGY OF THE EUREKA DISTRIOT. 
Agnostus bidens Meek. 
Plate ix, figs. 13, 13 4. 
Agnostus bidens Meek, 1873. Sixth Ann. Rep. U.S. Geol. Surv. Territories for the 
year 1872, p. 463. 
Cephalic shield, moderately convex; a little wider than long, distinctly 
trilobed and bordered by a rounded margin, with a rather strongly defined 
marginal groove. Glabella convex, narrow, more than two-thirds the 
length of the shield, converging anteriorly and rounded or subangular in 
front; a narrow, transverse furrow enters obliquely from each side poste- 
rior to the center and unites just in advance of a small tubercle on the 
center of a segment defined behind by a transverse furrow that bends back- 
ward at the center; between the latter furrow and the occipital furrow, a 
nurow segment widening out laterally, is distinctly defined; occipital seg- 
ment very narrow. Dorsal furrows distinct, united in front of the glabella 
but not touching the frontal border. Lateral lobes strongly convex and 
sloping rapidly to the marginal groove from the somewhat elevated central 
portion; frontal lobe about half as wide as the lateral lobes and less 
convex. 
Thoracic segments unknown. 
The caudal shield associated with the above-described head has all of 
its essential elements, and there is little doubt but that it belongs to the 
same species. It is provided with a short spine or process on each posterior 
lateral side and is strongly convex and trilobate; the axial lobe extends 
more than three-fourths of the entire length and has an elongate, angular 
node on the anterior portion, with a transverse furrow just before it separat- 
ing a narrow anterior portion, and in some examples a slight transverse 
furrow crosses just back of the node; this is obsolete in many instances. 
The dorsal furrows extend backward and unite posteriorly, giving the axial 
lobe a conical form; lateral lobes strongly convex and very much like 
those of the associated cephalic shield. Surface of both shields finely 
granulose under a strong magnifying power. 
