214 
PALAEONTOLOGY OF NEW YORK. 
which are distant from each other from 5 to 6 mm., very much depressed 
and destitute of cell apertures; the apertures immediately adjacent to the 
depressed portion are larger and much more oblique than on other parts of 
the frond. 
The surface varies in appearance according to the degree of preservation; 
when weathered the peristomes are stronger and more elevated, and the 
mesopores more conspicuous than when the frond is perfectly preserved; in 
the latter case the intermediate pits are very obscure. 
This species may be distinguished from F. variapora by the circular, slightly 
smaller and more distant cell apertures, the depressed centers of the monticules, 
the larger mesopores, and the more irregular vesicular structure; in the 
latter species they have the appearance of septate tubuli: from Lichenalia 
stellata by the deeper depression at the centers of the monticules, the smaller 
and more distant cell apertures, the equally elevated peristomes, the presence 
of mesopores, and the more irregular arrangement of the vesicles: from F. ser- 
rulata by the depression in the monticules, the larger and more oblique cells 
near their centers, the closer disposition of the apertures, and the absence of 
serrulations on the peristomes. 
Formation and locality. Hamilton group, York, Livingston county, N. Y. 
Fistulipora serrulata. 
PLATE LVIXI, FIGS. 6-8. 
Thallostigma serrulata, Hall. Trans. Albany Institute, vol. x, p. 185. 1881. 
“ “ “ Report of State Geologist for 1883, p. 20. 1884. 
Zoarium consisting of free or incrusting explanate fronds, or forming masses 
composed of successive layers of growth. Cells tubular, cylindrical, sep¬ 
tate, rectangular or slightly oblique to the surface, invariably opening 
directly outward; septa very infrequent or obsolete; cell walls com¬ 
paratively thick, longitudinally striated Intercellular tissue composed of 
vesicles, which are sometimes very irregularly, at other times regularly 
disposed, but not having the appearance of tubuli divided by septa as 
in many species, but of vesicles superimposed in somewhat regular order. 
