Genus Ag7iost us. — Vogdes. 395 



very indistinct, of conical form, with triangular basal lobes. 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 ^ 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 lower end. 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, Eun^ka District, Nevada. 



ASAPHUS ZONE. 



Section IV, ARTHRORHACHIS, type Agnostus tardus Barr. 

 Agnostus galea Billings, 1865. Plate ix, fig. 6. 



The author describes in The Palaeozoic Fossils of Canada, Vol. 

 1, 1865, p. 291, Agnostus gajlm and A. fahius 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. lentifonnis Ang. The species appear with the gen- 

 era Asajihus, lUeenus and Triarthrus Jischeri., etc. 



Diagnosis. — Head strongly convex. Limb narrow. Glabella 

 convex, strongly elevated above the general surface, occupying . 

 about f 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 ^ the length from the apex ; a short one on each side at f the 



