Genus Agnostus.— Vogdes. 393 
anterior portion, with a transverse furrow just before it, separating 
a narrow anterior portion; in some examples a faint transverse 
furrow crosses back of the tubercle. Surface of the head and 
pygidium finely granulose. 
Locality. Gallatin City, Montana, also in the Eureka District of Ne- 
vada and elsewhere. 
AGNostus TuMIDOsUS Hall and Whitfield, 1877. Plate x, fig 8. 
Diagnosis.—Head highly dome-shaped in outline, slightly con- 
tracted near the occipital border, very convex. Limb narrow, 
flattened. Dorsal furrow distinct. Glabella small, less than 3 
as long as the head, conical and very convex, especially tumid in 
the lower part; the central tubercle marked near its edge by a very 
slight line which presents the appearance of a border surrounding 
it. Frontal lobe about + of the length of the glabella. Basal 
lobes triangular and minute. Thorax unknown. The _ highly 
dome-shaped outline with the form and markings of the glabella 
distinctly mark this species. 
Locality. Kureka, Nevada. The species is of the type A. quadratus 
Tullberg. 
AGNOSTUS INTERSTRICTUS White, 1874. Plate x, fig. 6. 
Diagnosis.—This species of the type A. fallax Linrs. is ellip- 
tical in form with a smooth surface. The head is broader than 
long. Limb narrow, forming a narrow linear depression between 
it and that portion of the head which it incloses. Glabella bilobed, 
conical, well defined by the dorsal furrows, and sharply rounded 
in front. A minute tubercle on the median line; near the poster- 
ior end; the frontal lobe is marked off by a shallow transverse 
furrow. Thorax of two joints, narrower than the head and 
pygidium, giving the body the appearance of being constricted at 
the middle. Axis broad, both its joints.tumid at the ends, where 
they reach the dorsal furrows; lateral lobes very narrow, pleure 
about as wide as long, each pleurze tumid and rounded at the ex- 
tremities. Pygidium in form like the head. Axis a little longer 
than the glabella, moderately convex, with a minute tubercle on 
the median line near the anterior end. Sides between the mar- 
ginal furrow and axis convex. The lateral angles of the pygid- 
ium are produced into sharp spines, The basal lobes of the gla- 
bella are very minute. 
Locality. Antelope Springs, Utah. 
