210 
PALAEONTOLOGY OF NEW YORK. 
Fistulipora variapora. 
PLATE LVIII, FIGS. 9-14. 
Thallostigma variapora, Hall. Trans. Albany Institute, vol. x, p. 184. 1SS1. 
“ “ “ Report of State Geologist for 1883, p. 18. 1884. 
Zoarium consisting of explanate, free or incrListing fronds, or of masses formed 
by the superimposition of successive layers of growth; fronds from 1 to 15 
mm. or more in thickness; the under side consists of a thin, strongly 
wrinkled epitheca, from which the cells arise rectangularly to the surface. 
Cells tubular, cylindrical, septate ; septa thin, occurring at irregular, usually 
somewhat distant intervals. Intercellular tissue composed of vesicles, which, 
near the base, are irregular, becoming more regularly disposed above, and 
having the appearance of septate tubuli; septa very frequent, about sixty in 
the space of 5 mm. Cell apertures circular, obscurely triangular or trilobate, 
diameter .35 mm., irregulary disposed, sometimes in contact, usually distant 
about one-half the diameter of an aperture, frequently operculated; opercula 
smooth, solid and slightly convex at the center, with several radii extending 
to the peristome. Peristomes strong, equally elevated, when perfectly pre¬ 
served having two minute denticulations. Mesopores obscure; margins 
slightly elevated, diameter usually about one-half that of the cell aperture. 
The surface is marked by broad, rounded monticules, the centers of which are 
distant from each other about 5 mm., the bases nearly or quite in contact; 
a central space of 1 mm. in diameter is occupied by mesopores, which 
are smaller than those on other portions of the frond; the cell apertures 
immediately adjacent are larger than the others, having a diameter of .50 
mm., from twelve to fifteen of the larger cells on each monticule. 
This species most nearly resembles F. umbilicata, but the centers of the 
monticules are very slightly, if at all depressed, the space destitute of cell 
apertures is much smaller, and the apertures are a little larger, more distinctly 
trilobate and more closely disposed: from Lichenalia stellata it is distinguished 
by the absence of a pronounced depression at the centers of the monticules, by 
the equally elevated peristomes and the presence of mesopores: from F. con- 
