74 
PALAEONTOLOGY OF NEW YORK. 
Acanthoclema triseriale. 
PLATE XXVIII, FIGS. 5, <5. 
Stictopora triserialis, Hall. Report of State Geologist for 18S2. Expl. pi. 25 (xxviii), figs. 5, 6. 1883. 
Zoarium ramose, solid ; diameter ,50 mm.; bifurcations infrequent. Cell aper¬ 
tures oval, length .15 mm., width from one-half to two-thirds the length; 
disposed in longitudinal parallel rows; six rows in the circumference of a 
branch, separated by comparatively prominent ridges. 
This species may be distinguished by its slender branches, and minute cell 
apertures. 
Formation and locality. Upper Helderberg group, near Caledonia, N. Y. 
NEMATAXIS, Hall. 1886. 
Nemataxis fibrosus. 
PLATE XXV, FIGS. 30-36. 
Nemataxis fibrosa, Hall. Report of State Geologist for 1885, advance sheets. Expl. pi. 25, figs. 30-36. 1886. 
Zoarium ramose, solid; branches 4 mm. in diameter; bifurcations comparatively 
frequent. Cells tubular, polygonal, arising from a central filiform axis, 
diverging at an angle of forty-five degrees until within a short distance 
from the surface, when they abruptly turn outward. Cell walls in con¬ 
tact for nearly their entire length. Cell apertures oval, length .30 mm., 
width about one-half the length; closely disposed in longitudinal parallel 
rows, separated by prominent ridges; about thirty rows on a branch: per¬ 
istomes very thin, slightly elevated. At intervals of 3 mm. the surface is 
marked by monticules which are destitute of cell apertures, and extend across 
the branch, giving it an annulated appearance. The cell apertures are 
frequently obsolete, the surfaces being occupied by prominent longitudinal 
ridges. 
In a fractured specimen, near the base, exposing the interior below the sur¬ 
face, the stipe exhibits a compact fibrous texture. 
Formation and locality. Upper Helderberg group, Ontario, Canada. 
