FOSSILS OF THE LOWER SILURIAN. 91 
Genus PTYCHOPARIA Corda. 
Ptychoparia? annectans, n. sp. 
Plate xii, fig. 18. 
Head very small, semicircular; postero-lateral angles unknown. Gla- 
bella moderately convex, length and width subequal, broadly rounded in 
front; marked by three pairs of furrows, the anterior pair scarcely per- 
ceptible, median and posterior pairs distinctly but not deeply impressed; 
occipital ring narrow, rounded, without a spine; occipital furrow well de- 
fined; dorsal furrow narrow, distinct, and extending with equal force in 
front of the glabella; fixed cheeks rather wide, sloping with a gentle con- 
vexity to the minute eyelobes and into the frontal limb; frontal limb con- 
vex, curving rapidly downward, and bordered by a rounded rim; postero- 
lateral limbs narrow, and extended quite a little distance laterally, marked 
by a narrow groove in the posterior margin. 
Thorax and pygidium unknown. 
This little species is closely allied to P. minutus (Sixteenth Ann. Rep. 
N. Y. State Cab. Nat. Hist., p. 150, pl. viii, figs. 5-7, 1861) of the Potsdam 
sandstone of New York, and the allied P. minor (Ibid, p. 149), from the 
same horizon in Wisconsin. It differs in the shorter glabella, absence of 
nuchal spine, and larger frontal limb. It is interesting as occurring in 
association with the preceding species, and as terminating the upper limit 
of the range of the genus in the Prospect Mountain section. 
Formation and locality.—In the lower portion of the Pogonip Group on 
the east slope of the ridge next east of the Hamburg Ridge, Eureka Dis- 
trict, Nevada. 
Genus BATHYURUS Billings. 
Bathyurus? tuberculatug, n. sp. 
Plate xii, fig. 9. 
Glabella conical, strongly convex and elevated above the fixed cheeks; 
occipital segment narrow, elevated on the posterior margin, and with a short 
spine projecting backward and a little upward from the center; occipital 
