CORALS AND BRYOZOA. 
95 
Stictopora semistriata. 
PLATE XXVIII, FIGS. 17-20. 
>Stictopora semistriata , Hall. Trans? Albany Institute, vol. x, abstract, p. 14. 1881. 
“ “ “ Report of State Geologist for 1882. Expl. pi. 28, figs. 17-20. 1883. 
Zoarium consisting of dicliotomously branching, flattened stipes; transverse 
section lenticular; width of branches about 3 mm., margins divergent; 
greatest thickness .50 mm.; bifurcations moderately frequent. Cell aper¬ 
tures nearly or quite circular, diameter .30 mm.; marginal apertures slightly 
larger than the others; more or less distinctly disposed in longitudinal rows, 
which increase by interstitial addition, the rows being sometimes separated 
by narrow ridges, at other times the space between them is smooth and the 
apertures appear irregularly disposed. Peristomes thin, sometimes equally 
elevated, but usually the anterior portion is slightly and the posterior portion 
more strongly elevated, frequently with slight denticulations. 
This species closely resembles S. Gilberti, but the fronds are somewhat nar¬ 
rower, much thinner, the margins of the branches are more nearly parallel, the 
cell apertures are circular, more irregularly disposed, and the branches are fre¬ 
quently without longitudinal ridges. It may perhaps be only a variety of 
that species. 
Formation and locality. Upper Helderberg group, west of Le Roy, N. Y. 
Stictopora riiomboidea. 
PLATE XXIX, FIGS. 27, 28. 
Stictopora riiomboidea, Hall. Trans. Albany Institute, vol. x, abstract, p. 15. 1881. 
“ “ “ Report of State Geologist ^for 18S5, advance sheets. Expl. pi. 29, tigs. 27, 
28. 1886. 
Zoarium consisting of a flattened, dicliotomously bifurcating frond; width of 
branches 2 mm., margins essentially parallel; transverse section elliptical; 
greatest thickness 1 mm. Cell apertures oval, length .33 mm., width two- 
thirds the length; disposed in longitudinal rows, usually alternating. Ranges 
of apertures separated by very sinuous ridges, which are frequently anasto¬ 
mosing, giving to the aperture the appearance of being surrounded by a rhom- 
