Fauna of the Morrow Group 
129 
spaces immediately thereafter, rounded and longitudinally stri- 
ated ; on the obverse face the branches are very little wider and 
are marked by a distinct mesial keel separating the two ranges 
of zooecia. Dissepiments typically slightly narrower than the 
branches, and depressed somewhat below them; at right angles 
to the branches and broadening at the ends in the basal portion 
of the zoarium, more frequently oblique in the outer portions. 
Fenestrules 91/2 or 10 to the centimeter, oval or circular toward 
the base of the frond, ordinarily subquadrate or diamond-shaped 
toward the upper margin, 0.4 to 0.6 mm. long and 0.3 to 0,6 mm. 
wide, size and shape similar on either face of the zoarium. 
Zooecia in 2 ranges separated by a median keel, on the branches ; 
3 to 6, commonly 4, on each dissepiment ; apertures circular and 
closely adjacent in the rows, 27 or 28 occurring in 5 mm. along 
the branches. Accessory pores numerous on the reverse face of 
the frond, generally 4, but varying from 2 to 5, on each dissepi- 
ment situated more commonly in pairs at either end; about 0.1 
mm. in diameter. 
Remarks, This species displays many resemblances to *8. 
cestriensis, common in the Chester of the Mississippi valley and 
identified by Condra from the Coal Measures of Nebraska, but 
from that form it is distinguished by its somewhat larger fenes- 
trules and more numerous accessory pores as well as by the 
greater number of zooecial apertures in a unit distance. Unfor- 
tunately the only specimen at hand is not preserved so as to 
permit the determination of the presence or absence of nodes 
along the mesial carina. 
Horizon and locality. Hale formation: East Mountain, Fay- 
etteville, Arkansas (Station 136). 
Septopora implexa n. sp. 
Plate VI, figure 12. 
Description, Zoarium a foliar expansion composed of primary 
and secondary branches united at more or less regular intervals 
by poriferous dissepiments into an undulating network. Pri- 
mary branches 0.6 to 0.8 mm. in width, nearly rigid, giving off 
secondary branches by lateral division at an angle of about 35° 
and typically with 8 branches in a centimeter ; secondary 
branches 0.4 to 0.6 mm. in width and connected by arching dis- 
