20 
PALAEONTOLOGY OF NEW YORK. 
tudinal strife caused by the recumbent portion of the cells. Cells tubular, 
sub-cylindrical, arising from the epitheca and for about one-half their length 
parallel with it, then abruptly turning outward and opening obliquely to the 
surface. Apertures oval, length .25 mm., width slightly less; more or less 
regularly alternating and imbricating. Posterior margin strongly elevated, 
projecting over and concealing a portion of the opening; sometimes with 
two minute denticulations. 
There are frequent maculae destitute of cell apertures; the apertures 
immediately adjacent to these being larger than the others and radiating 
from the maculae. 
This is a very common species and can be easily recognized by the strong 
projecting lip of the cell apertures, the prominent maculae and the arrangement 
of the cells. 
Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 
Diamesopora dispersa. 
PLATE X, FIGS. 20, 21. 
Tremairtpora dispersa, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 150. 1879. 
“ “ “ Report of State Geologist for 1882. Expl. pi. 10, figs. 20, 21. 1883. 
Zoarium ramose; branches hollow, diameter 3 mm. Thickness of the bryo- 
zoum .75 mm. Inner surface covered by a transversely wrinkled epitheca. 
Cells tubular, opening slightly oblique to the surface. Apertures circular or 
oval, diameter .30 mm., irregularly disposed, sometimes forming transverse 
rows: margins thick, distinctly and sometimes, equally elevated; at other 
times the lower portion is the more strongly elevated, giving to the aperture 
a sub-triangular appearance. 
There are occasional maculse destitute of cell apertures, the cells, imme¬ 
diately adjacent, radiating from them. 
This species differs from D. constricta in the cell apertures being less oblique 
and more irregularly arranged. 
Fonnation and locality. Lower Helderberg group, near Clarksville, N. Y. 
