202 
PALEONTOLOGY OF NEW YORK. 
Lichenalia cultellata. 
PLATE LXIV, FIGS. 1, 2. 
Lichenalia cultellata, Hall. Report of State Geologist for 1883, p. 35. 1884. 
Zoarium consisting of explanate fronds, free or incrusting other objects, thick¬ 
ness usually about 1 mm. No masses formed by the superimposition of 
successive layers of growth have been observed. Cells tubular, cylindrical 
rectangular or oblique to the surface, non-septate, walls very thin. Inter¬ 
cellular space vesiculose, vesicles comparatively very large, usually irregu¬ 
larly disposed, sometimes more irregularly superimposed, but in the speci¬ 
mens observed, never appearing as walled, septate tubuli. Cell apertures 
trilobate or trifoliate, the posterior lobe or fold is remarkably well devel¬ 
oped, being much larger than the other two combined, length .30 mm., 
width three-fourths the length, radiating from the center of the monticules, 
forming irregular, intersecting rows. Peristomes thin, posterior portion the 
more strongly elevated and with two moderately prominent denticulations. 
Interapertural space flat, smooth. Surface marked by strongly elevated, 
obtusely conical monticules, the centers of which are distant about 5 mm., 
irregularly disposed; on one side of the monticule, commencing at the 
center and extending to the base, there is a narrow, gradually enlarging 
depression; the apertures nearest the center are slightly larger than the 
others, and extending from the center of the monticules to these apertures 
there are sharply angular, gradually enlarging, prominent ridges ; this feature 
gives to the cell the appearance of being so oblique that the upper portions 
of their walls are exposed for the entire length, but a section shows that 
they are only slightly oblique. In a transverse section the trilobate form 
of the cells is more conspicuous; the interapertural vesicles vary greatly in 
size and are frequently larger than the cell apertures. 
The cell apertures of the specimen from which tig. 1, pi. 64, was made do 
not show the usual trilobate form. 
The strong monticules and prominent ridges extending from their centers 
to the adjacent apertures are features which distinguish this species from any 
