340 The American Geologist. December, 1902. 
smooth, wider than the zooecial apertures ; thickened interspaces or 
small areas without apertures occur on the surface of the zoarium 
placed about 2 mm. apart- Zooecia quite vertical in the axial region 
and then bend slowly outward to the surface where they are not yet 
direct ; walls thin ioi the immature region, thickened in the periphery ; 
by vertical sections, narrow cortical and wide axial regions are shown. 
Tubes in the axial region, subcircular in section ; walls 0.02 mm. thick. 
Owing to the thickened walls in the outer portions, the zooecial cavi- 
ties decrease slightly in size inear the apertures. Acanthopores quite 
numerous, not long, small and large, generally small, forming in sec- 
tions, irregular circles about the zooecia, ten to fifteen in a circle ; they 
do not in any way form divisional lines in the zooecial walls; a few 
acanthopores, 0.06 mm. in diameter, occur at the angles of the cells ; 
small acanthopores 0.02 to 0.04 mm. in diameter. Tabulae scarce, ab- 
sent in most zooecia. Mesopores few and small. 
On account of the even cylindrical surface, few zooecia, and wide 
interspaces, this species is not apt to be confused with any of the as- 
sociated species of Rhombopora. The interspacial areas, i to 2 mm. 
apart, when present, will also serve in its identification. On account 
of the few large acanthopores resembling those of R. lepidodendroides 
Meek, the specimens may be confused with that species. Other char- 
acters enumerated will amply serve for distinction. It is clearly dis- 
tinct from all described species of Batostomella. Few specimens have 
been collected. One was sent to E. O. Ulrich who pronounced it new 
and a member of the genus Batostomella. The name is suggested by 
the even surface. Type specimens in the museum of the University of 
Nebraska, Lincoln., Nebraska. 
Position and locality: Coal Measures; South Bend, and Bennett, 
Nebraska. 
Stenopora heteropora n. sp. 
PI. XX. Figs. 1, 2. 
Zoarium massive ; surface with clusters of elevated apertures larger 
than the average; clusters 1.5 mm. across, 4 or 5 mm. apart. Aper- 
tures polygonal or rhomboidal, more or less in series about the clus- 
ters, 0.24 to 0.4 mm. across, average 0.26 to 0.3 mm., fourteen or fifteen 
in smni. Interspaces thin, 0.05 to 0.06 mm. wide. Zooecia about 3 mm. 
long, at first horizontal, and then with a quick curve, they pass direct 
to the surface ; tubes polygonal, average diameter 0.27 mm., walls thin, 
usually not more than 0.02 mm. thick; near the surface they increase in 
thickness equal to that of the interspaces. Diaphragms thin, 5 to 8 in 
each tube, about 0.26 mm. apart in the straight portion of each tube. 
Acanthopores few, of medium size, located at the cell angles. The 
line of division between the adjacent zooecia is quite plain. The 
writer knows of no species of the genus more closely related to Aniso- 
trypa. 
The nearest related species is S. rudis Ulrich from which this dif- 
fers mainly in zoarial form. The zoarium of that species consists of 
