82 
PALEONTOLOGY OF NEW YORK. 
lete; posterior margin strongly elevated, slightly denticulated, projecting 
over and partially concealing the opening. The' surface contiguous to the 
posterior margin is convex, giving to the apertures the appearance of small 
openings in the side of a rounded elevation. Monticules destitute of cell 
apertures, their centers distant from each other about 4 mm. Intercellular 
space occupied by irregular vesicles or septate tubuli; space beneath monti¬ 
cules without interior structure. 
This species may be distinguished by the hemispherical monticules and the 
sub-imbricating appearance of the cell apertures. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Lichenalia permarginata. 
PLATE XXVI, FIG. 20. 
Lichenalia permarginata, Hall. Trans. Albany Institute, vol. x, abstract, p. 10. 1881. 
“ “ “ Report of State Geologist for 1882. Expl. pi. 24, fig. 20. 1883. 
Zoarium consisting of lamellate expansions; thickness of the specimens observed 
.50 mm. Cell apertures circular, diameter .40 mm.; irregularly and not 
closely disposed: peristomes strong, distinctly and equally elevated. Surface 
marked by non-celluliferous maculae, which are distant from each other 7 
mm. ; the apertures immediately adjacent being slightly larger than on other 
portions of the frond. Surface where well preserved finely granulose. 
Formation and locality. Upper Helderberg group, Onondaga Valley, Onondaga 
county, N. Y. 
PlLEOTRYPA, S. g. 
Lichenalia (Pileotrypa) pyriformis. 
PLATE XXXI, FIGS. 21-27. 
Lichenalia pyriformis, Hall. Trans. Albany Institute, vol. x, abstract, p. 12. 1881. 
“ (Pileotrypa) pyriformis. Report of State Geologist for 1885. Expl. pi. 31, figs. 21-27. 1887. 
Zoarium consisting of thin lamellate expansions incrusting other objects. On the 
thinner portions of the frond the cells are very oblique, sometimes a portion 
of the walls being exposed for nearly the entire length, presenting a pyri- 
