24 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
glabella tapers into a spine, this feature not being correctly shown by 
Weller’s figures. I had at first believed that this specimen repre- 
sented a distinct species, but fortunately was able to see the type in 
Mr. Teller’s collection. That the species belongs to Trochurus in- 
stead of Dicranopeltis is shown by the dorsal furrows, which curve 
inward instead of outward, at the posterior ends. 
Formation and locality: —'The specimen is from the Niagaran at 
Wauwatosa, Wisconsin. 
. 
ODONTOPLEURIDAE Burmeister. 
CERATOCEPHALA GONIATA Warder. 
Plate 3, fig. 3-5. 
Ceratocephala goniata Warder, Amer. journ. sci., 1838, ser. 1, 34, p. 378, fig. 
Clarke, 44th Rept. N. Y. state mus. nat. hist., 1892, p. 91-100, pl. 1, 
f. 1. Kindle, 28th Ann. rept Dept. geol. and nat. res. Indiana, 1904, 
p. 480, pl--24, f. 138. Weller, Bull. Chicago acad. sci., 1907, no. 4, pt. 2, 
p. 255, pl. 23, f. 1-2. Raymond, Bull. Victoria mem. mus., 1913, 1, p. 38. 
Acidaspis danai Hall, Geol. surv. Wisc., 1862, 1, p. 432 (no description); 18th. 
Rept. N. Y. state cab. nat. hist., 1865, p.28, adv. sheets; 20th Rept. N. Y., 
state cab. nat. hist., 1868, p. 333, pl. 21, f. 8-9; 1870, rev. ed., p. 423, 
pl. 21, f. 8, 9. 
Acidaspis ida Winchell and Marcy, Mem. Boston soc. nat. hist., 1865, 1, p. 
106, pl. 3, f. 13. 
The cephalon of this species is, thanks to Professor Weller, now well 
known, but hitherto the thorax and pygidium have not been noticed. 
The Day collection in the M. C. Z. contains parts of two pygidia and 
a fragment showing a portion of five segments of the thorax. The 
pygidium is like that of Acidaspis portlocki Barrande, with a large 
median spine, on each side of which are two smaller spines, then a 
large spine, and finally an outer small spine. Each spine gives off 
small thorns on each side. The thorax is similar to that of C. verneualr 
Barrande. However, as only the central portion has been seen this 
part of the body would not be expected to show specific characteristics. 
The cephalon seems to be more nearly allied to C. vesiculosa than to C. 
verneuili, and a cephalon in the M. C. Z. gives indication that marginal 
spines were present on the free cheeks. The pygidium found with the 
cranidia at Wauwatosa are unlike those ascribed to C. vesiculosa by 
