232 
PALEONTOLOGY OF NEW YORK. 
guished by the smaller, sub-polygonal, more closely disposed cell apertures, and 
its maculse of larger cell apertures: from F. micropora and F. segregata by the 
much more closely disposed cell apertures, and the fewer mesopores, which 
never entirely surround an aperture. 
Formation and locality. Hamilton group, York, Livingston county, N. Y. 
FlSTULirORA DECIPIENS. 
PLATE LIX, FIG. 9. 
Thallostigma decipiens, Hall. Trans. Albany Institute, vol. x, p. 1S7. 1881. 
“ “ “ Report of State Geologist for 1883, p. 29. 1884. 
Zoarium consisting of lamellate expansions, incrusting other objects, usually 
Cyathophylloid corals. Cells tubular, cylindrical, oblique or rectangular to 
the surface, always opening directly outward; the septa occur more fre¬ 
quently near the surface than in the lower portion of the cell tubes. Inter¬ 
cellular tissue vesiculose, vesicles comparatively large, and irregularly dis¬ 
posed near the base, more regularly superimposed above, but not having the 
appearance of septate tubuli, from four to six in the space of 1 mm. 
measured longitudinally. Cell apertures polygonal or sub-polygonal, diame¬ 
ter from .25 to .30 mm., irregularly disposed, sometimes in contact, at other 
times separated by nearly twice the diameter of an aperture. Peristomes 
thin, equally elevated. Mesopores variable in form and size, sometimes 
minute, at other times equal in diameter to the cell apertures; margins 
of the same height and thickness as the peristomes. Surface marked by 
broad, slightly elevated monticules, upon which the cell apertures and meso- 
pores are of the same size as on other portions of the frond. 
When the frond is well preserved it is frequently very difficult to distinguish 
the cell apertures from the mesopores, both being polygonal and often of the 
same size, the surface resembling that of a Palesciiara ; when the frond is 
worn the appearance is very different, the apertures being larger, less angular, 
more nearly circular, and much more conspicuous than the mesopores : without 
a very careful examination, it would naturally be supposed that this appear¬ 
ance of the fossil was due to an extremely thin Paleschara incrusting a 
Fistulipora, some portions being worn away, showing the Fistulipora be- 
