Fauna of the Morrow Group 
117 
from 21 to 23 apertures are present in each 5 mm. of longitudinal 
space, the individual apertures being separated by spaces one- 
half to two-thirds as great as their diameters. 
Remarks. This species is comparable to only two of the previ- 
ously described Carboniferous members of the genus, P. whitei 
and P. biseriata. From the former it is distinguished by the 
closer arrangement of the apertures, their relatively larger diam- 
eter, and the less elongated fenestrules as well as by the greater 
persistence of the triseriate arrangement of the zooecia. Like 
P. tvhitei, it may be considered as a link between Fenestella and 
Polypora. From P. biseriata this species is distinguished by the 
absence of the central row of nodes and by the fact that the 
arrangement of zooecia in three ranges is normal instead of 
rare, as in the Mississippian form. 
Horizon and locality. Hale formation: East Mountain, Fay- 
etteville, Arkansas (Station 136). Brentwood limestone: in the 
vicinity of Fayetteville, and near Brentwood, Arkansas (Stations 
135, 148, 150, and 145). 
Polypora elliptica Rogers 
1900. Polypora elliptica. Rogers, Kans. Univ. Quart., vol. 9, p. 7, pi. 4, 
fig. 2. 
Upper Coal Measures: Kansas City, Missouri; Argentine, Law- 
rence, and Topeka, Kansas. 
1903. Polypora elliptica. Condra, Nebr. Geol. Surv., vol. 2, pt. 1, p. 69, 
pi. 11, figs. 4-11; pi. 12, figs. 1-13; pi. 16, fig. 3. 
Coal Measures: Kansas City, Missouri; Argentine, Lawrence, and 
Topeka, Kansas; several localities, Nebraska. 
Permian: Blue Springs, Nebraska. 
A small fragment of a foliar, fan-shaped expansion from the 
Brentwood limestone seems to be indistinguishable from some 
of the forms included in this very variable species. As usual, 
the obverse face only is exposed. The branches are subcarinate, 
somewhat flexuous and about 2.5 mm. in width, with 14 to 16 
occurring in the space of 1 cm. The dissepiments are the same 
shape and about half as wide as the branches and slightly de- 
pressed below them. The fenestrules are sub-oval to circular 
in outline, 0.3 to 0.4 mm. wide and 0.4 to 0.6 mm. long, with 12 
or 13 to the centimeter. By grinding down the fragment it 
was ascertained that the zooecia are sometimes in two, but more 
