210 PALEONTOLOGY OF NEW YORK. 



FiSTULIPORA VARIAPORA. 



PLATE LVm, FIGS. 9-14. 



Thattostigma variap<mi. Hall. Tnin.s. Albany Institute, vol. x, p. 184. 1881. 

 " " " Report of State Geologrist for 1883, p. 18. 1884. 



ZoARnjM consisting of explanate, free or incrusting fronds, or of m.asses formed 

 by the superimposition of successive layers of growth ; fronds from 1 to 1 5 

 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 Lichmalia 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. cm- 



