342 The American Geologist. December, i9ol'. 
and then continue direct to the surface. Walls, in the immature por- 
tion, very thin, 0.02 mm. thick; not moniliform ; in the cortical por- 
tion they are evenly thickened and finely laminated. The small acan- 
thopores are 0.04 to 0.07 mm. in diameter and more numerous than 
in other species collected in the state ; they form in sections one com- 
plete series about each zooecium, with twelve to twenty in a series; 
at places, two or more incomplete rows are observed. A few large 
acanthopores occur at the angles of some of the zooecia. The zooecial 
cavity is about equal in diameter throughout. Diaphragms, few in 
number, not more than one to each zooecium, generally placed at the 
inner border of the mature portion of each tube which is i to 1.5 mm. 
thick. Mesopores small, irregular in form, about one-fourth as nu- 
merous as the zooecia. 
The writer is in doubt about the systematic position of this species. 
It may belong to Stenopora, Batostomella or Rhombopora. When 
someone establishes the limits of these genera, it can be correctly 
placed. Rhombopora crassa Ulrich has a thicker cortical portion, no 
large acanthopores, and the zooecia are not vertical in the axial region. 
There are not enough large acanthopores to place it with R. lepido- 
dendroides Meek : also, other characters, such as the zoarial form and 
quick transition from the immature to the mature region, make it dis- 
similar. The apertures are not like those of most species of Batosto- 
mella, but the walls, mesopores, and small acanthopores resemble to 
a degree the same of that genus. The apertures, acanthopores and 
mesopores as a whole seem to be nearer those of Stenopora than to 
either of the other genera. The species may be a Rhombopora related 
to R. crassa and R. lepidodendroides. Further, it may be a peculiar 
form of an old growth of the latter. Type specimens in the museum 
of the University of Nebraska, Lincoln, Nebraska. 
Position and locality: Coal Measures; South Bend. Nebraska. 
Fenestella cyclofenestrata n sp. 
PI. XXI. Figs, 1-3. 
Zoarium a reticulate expansion apparently of large size; of a num- 
ber of incomplete zoaria, each over 4 cm. across. Branches straight 
or slightly flexuous, average width 0.25 mm., twelve to fourteen in 5 
mm., 0.35 mm. wide immediately below bifurcations which are far 
apart and with very acute angles ; reverse face evenly and slowly 
rounded, smooth or faintly striated ; the obverse shows a broad, evenly 
elevated area 0.07 to o.i mm. across; spines not observed to be present. 
Frequenth"- the area is more elevated and appears as a broad carina. 
Dissepiments on the reverse face, as wide as long, over one-half 
as wide as the branches, on a level with the latter, much expanded 
terminally ; they and the branches slope evenly to the fenestrules ; 
not much depressed and strong on the obverse. Fenestrules on the 
reverse, circular or subcircular, modified by the terminalh^ expanded 
dissepiments, average 0.2 mm. long, about twelve in 5 mm. ; a little 
longer and less wide on the opposite face. 
