92 PALAEONTOLOGY OF NEW YORK. 



tially parallel; non-celluliferous space at the margin very narrow; greatest 

 thickness .Go mm. ; bifurcations infrequent. Cell .apertures oval, length .25 

 mm., width from one-half to three-fourths the length ; marginal apertures 

 slightly larger than the others; all disposed in longitudinal parallel rows, 

 which are separated by prominent, sharply angular, fi)iely striated ridges. 

 Peristomes thin, slightly and equally elevated; denticulated; denticulations 

 moderately strong and situated on the posterior portion of the peristome. 



This species may be distinguished from S. crescens, which it most nearly 

 resembles, by the very narrow, smooth, non-celluliferous space at the margin, 

 the angular longitudinal ridges, and the denticulations of the cell apertures. 

 The position of the denticulations on the posterior portion of the aperture, 

 will distinguish it from nearly all the denticulated forms. 



Formation and locality. Upper Helderberg group, west of Le Roy, N. Y. 



Stictopoka fruticosa. 



PLATE XXVIH, FIGS. li-H. 



StUitrpora fruticosa, Hall. Traus. Albany Institute, vol. x, abstract, p. 14. 1881. 



Report of State Geologist foi' ISS2. Expl. pi. 25, figs. 12-14. 1883. 



ZoARiUM consisting of a flattened, dichotomously branched, fruticose stipe ; 

 transverse section lenticular; width of branches from 2.50 to 3 mm., mar- 

 gins nearly parallel; greatest thickness from .80 to 1.20 mm. Cell apertures 

 oval, length .40 mm., width one-third the length ; marginal ones larger than 

 the others ; all disposed in parallel longitudinal rows, six or seven rows on 

 each face of a branch. Surface between apertures obscurely striated, granu- 

 losa, elevated, resembling ridges. Peristomes thin, slightly elevated, granu- 

 lose, not denticulated. 



The appearance of the surface varies according to the condition of the 

 frond ; when much weathered the apertures are enlarged, frequently polyg- 

 onal, sometimes giving to the surface a reticulated appearance. 



This species may be distinguished by the narrow elongate cell apertures, the 

 granulose elevations between the ranges of apertures, and the frequent bifurca- 

 tions, which give to the frond a fruticose appearance. 



Formation and locality. Upper Helderberg group, N. Y. 



