Fauna of the Morrow Group 
125 
Polypora anastomosa n. sp. 
Plate VI, figures k, 
Description. Zoarium a funnel-shaped or foliar, reticulated 
expansion composed on the reverse of flexuous, somewhat irreg- 
ular branches, united by broad dissepiments, in such a way that 
individual branches can be traced only with great difficulty while 
on the obverse the branches are practically anastomosing. 
Branches massive, irregularly sub-carinate, granulose, 0.4 to 0.8 
mm. wide on the reverse ; broadly convex, 1.0 to 1.3 mm. wide on 
the obverse; about 6 to a centimeter transversely. Fenestrules 
sub-polygonal to sub-oval on the reverse, 1.1 to 1.5 by 0.8 to 
1.3 mm. in diameter, 31/2 to 4 in a centimeter longitudinally; 
smaller on the obverse, oval in shape and usually about 0.8 by 
0.5 mm. in size. Dissepiments of variable length depending upon 
the sinuosity of the branches, but typically less than 1.0 mm* 
long and about 1.5 mm. wide on the reverse ; shorter and broader 
on the obverse where they average 2.0 mm. in width and are less 
than 0.5 mm. long, and the zooecial apertures encroach upon them 
from the adjacent branches until in some instances no non- 
poriferous portion remains. Zooecia in 5 to 7 flexuous rows, in 
some instances increasing to 9 or decreasing to 4; apertures 
small, circular, about 20 in 5 mm. in the ranges and separated 
by spaces about twice as great as their diameters. 
Remarks. The forms placed under this head are to be grouped 
with P. reversispina as transitional between the genera Polypora 
and Phyllopora. Resemblances to P. transiens are close but the 
two species are readily distinguished by the more flexuous 
branches and wider dissepiments of the Morrow form. 
Horizon and locality. Hale formation: East Mountain, Fay- 
etteville, Arkansas (Station 136). Brentwood limestone: vicin- 
ity of Fayetteville, Arkansas (Stations 135 and 150). 
Polypora anastomosa var, spinicarinata n. var. 
A fragment of a frond from the same locality as that which 
supplied the type of P. anastomosa seems to represent a distinct 
variety of that species. The arrangement of the zooecial aper- 
tures is the same as in the half dozen specimens of the typical 
variety but from them it differs in the generally more robust 
nature of the branches and dissepiments and in the presence of 
