Genus Agnostus.— Vogdes. 895 
very indistinct, of conical form, with triangular basallobes. Limb 
narrow, somewhat rounded, gradually fading out along the postero- 
lateral angles. Pygidium (?) much like the head, but much shorter 
in proportion to its width. The axis occupies more than 4 of the 
width, short and rounded, obconical, ornamented by a node in its 
upper end, and divided across by a doubly curved transverse fur- 
row near the lowerend. Dorsal furrows distinct. Limb flattened. 
Locality. Eureka, Nevada. 
Section FALLACES. 
AGNOSTUS SECLUSUS Walcott, 1884. Plate x, fig. 16. 
Diagnosis. —Head strongly convex, a little longer than wide, 
with a slight contraction posteriorly. Limb narrow with a distinct 
groove between it and the cheeks. Dorsal furrows well defined. 
Basal lobes distinct. Glabella about half the length of the head, 
‘strongly convex and squarely truncated in front; at about the an- 
terior third a broad, short furrow penetrates on each side a short 
distance, and posteriorly a rounded node is separated from each 
lateral angle by slight furrows, forming the basal lobes. The 
cheeks slope rapidly towards the marginal groove, on the sides 
and more gradually to the front. Surface finely granulose. 
Locality. Secret Canon shales, Eureka District, Nevada. 
ASAPHUS ZONE. 
Section BY. ARTHRORHACHIS, type Agnostus tardus Barr. 
AGNOosTUS GALBA Billings, 1865. Plate 1x, fig. 6. 
The author describes in The Palzozoic Fossils of Canada, Vol. 
1, 1865, p. 291, Agnostus galba and A. fabius from Table Head 
and Pistolet bay, Newfoundland. Both these species are of 
Lower Siluric types, the first of Agnostus tardus Barr, and the 
second of A. /entiformis Ang. The species appear with the gen- 
era Asaphus, Ilenus and Triarthrus fischeri, ete. 
Diagnosis.—Head strongly convex. Limb narrow. Glabella 
convex, strongly elevated above the general surface, occupying 
about 2 of the whole length of the head. Smooth, no tubercle, 
but with slight indentations on each side, at about the mid-length. 
Dorsal furrows distinct. Basal lobes triangular. Pygidium in 
‘contour and convexity, like the head. Axis strongly convex, well 
defined all round by the dorsal furrows; a furrow runs all across 
at 4 the length from the apex; a short one on each side at 2 the 
