1888. | NEW YORK ACADEMY OF SCIENCES. 249 
the centre of the ribs and axial rings. Limb of pygidium nar- 
row and apparently smooth. 
Geological position and locality.k—Waverly series, Sedalia, 
Mo., cabinet of F. A. Sampson. 
Affinities and differences.—This small pygidium approaches 
in general Griffithides seminiferus, Phillips, from the English car- 
boniferous limestone of Yorkshire, which has twelve axial rings 
and nine side ribs; the surface being ornamented by asingle row of 
tubercles along the centre of each axial ring and side rib; eight 
to ten on axis and about eight on each side rib. The American 
species is much smaller in size, and has a greater number of 
tubercles, with an arched anterior margin instead of the straight 
one usually found on Phillips’ species. Compared with Ameri- 
can tuberculated forms. this species differs from Phillipsia 
tuberculata, Meek and Worthen, first by having a less number 
of axial rings (twelve instead of sixteen or seventeen), and also 
varies in the number of side ribs (ten instead of fourteen). The 
surface of P. tuberculata is marked with six small tubercles, 
arranged on the axial rings so as to form six rows, and the side 
lobes are each ornamented by a row of tubercles along the ribs, 
varying from twelve to two, according to their length. 
On Griffithides (?) Sedaliensis the test of the pygidium is 
ornamented by a row of tubercles running across the axial - 
rings, varying from twelve to three according to the length of 
the rings. On the side ribs the number of tubercles varies, ac- 
cording to length, from eleven to three. The space immedi- 
ately in rear of the axis is also ornamented in the same manner. 
The pygidium of Phillipsia insignis, Winchell, has twelve to 
fourteen axial rings, each bearing six small tubercles, the whole 
of which are arranged in six longitudinal rows, and ten side ribs. 
From this species our specimen can also be readily distinguished 
by its surface markings. 
Compared with the pygidium of Phillipsia trinucleata. Her- 
rick (Bull. Se. Lab. Denison Univ., Vol. II., 1887, p. 64), our 
species has a less number of axial rings, twelve instead of seven- 
teen to nineteen, and a like variation in the number of ribs. 
The marginal limb of this species is broad and longitudinally 
striated, whereas our species has a narrow limb, apparently 
smooth. 
This last characteristic has prevented us from comparisons 
under the genus Brachymetopus appearing in the Waverly 
roup. 
F If Griffithides Sedaliensis is a true Griffithides (as its affinities 
with G. seminiferus indicate), we have in these Sedalia beds a 
very early appearance of a genus which heretofore was only 
known to the Keokuk, Chester, and Upper Coal Measures. We 
