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Kirtley F. Mather 
a distinct row of small circular spines, commonly about three 
to a fenestrule, along the middle of the sub-carinate reverse side 
of the branches. The branches are, also, somewhat more rigid 
and distinct than in the typical variety. 
Horizon and locality. Hale formation: East Mountain, Fay- 
etteville, Arkansas (Station 136). 
Genus PHYLLOPORA King 
Phyllopora perforata n. sp. 
Plate y, figures 5, 5a. 
Description. Zoarium a rapidly expanding, probably some- 
what funnel-shaped, reticulated expansion composed of anas- 
tomosing branches so completely intergrown that the whole 
appears as a plate perforated at fairly regular intervals by oval 
fenestrules arranged in more or less definite rows. Rows of 
fenestrules separated by spaces 0.7 to 0.9 mm. in width; in the 
rows the fenestrules are about 1.3 to 1.5 mm. apart, typically 6 
of them occurring in a distance of 10 mm. ; fenestrules compara- 
tively small, oval in shape, 0.3 to 0.45 mm. wide, 0.4 to 0.7 mm. 
long. Zooecial apertures scattered over surface of frond without 
definite arrangement either in longitudinal or oblique ranges; 
not present in a space about 0.15 mm. wide which forms the 
periphery of each fenestrule ; apertures small, circular, about 20 
to 22 occurring in a square millimeter. Zoarium thickened at 
the base and zooecial apertures closed in the thickened region 
as in Polypora corticosa. 
Remarks. Only one fragment, about 13 by 12 mm. in size, of 
this species is present in the Morrow collections but its char* 
acteristics as described above distinguish it sharply from all j 
described Carboniferous bryozoa of North America and it is 
referred with considerable confidence to the genus Phyllopora 
represented by several species in the Permian of Great Britain 
and India as well as by a few Silurian and Devonian forms. Two 
discrepancies ought, however, to be noted in the comparison of 
the material at hand with King's diagnosis^^ of his genus and its 
interpretation by Waagen and Pichl.^^ The first, which may be 
of some importance, is that in P. perforata the zooecial cavities 
ascend obliquely from the non-poriferous side to the obverse face 
and are not approximately vertical to the latter as they are in ||i 
