CORALS AND BRYOZOA. 
227 
the superimposition of successive layers of growth, while in this species the 
cell tubes continue from the base to the surface without interruption; the 
apertures are usually oval or sub-trilobate, and the mesopores are larger and 
more variable in shape. 
Formation and locality. Shales of the Hamilton group, York, Livingston 
county, N. Y. 
Fistulipora constricta. 
NOT FIGURED. 
Lichenalia constricta, Hall. Trans. Albany Institute, vol. x, p. 188. 18SI. 
“ “ “ Report of State Geologist for 1883, p. 36. 1884. 
Zoarium consisting of explanate fronds, encrusting other bodies, generally 
Cyathophylloid corals and Crinoid columns, or of masses formed by the accre¬ 
tion of successive layers of growth. Cells tubular cylindrical, rectangular 
to the surface, non-septate ; walls thin. Interapertural space vesiculose, near 
the base the vesicles are comparatively large and irregularly disposed, being 
much smaller and more regularly superimposed above, frequently appear¬ 
ing like septate tubuli, from sixty to one hundred septa in the space 
of 5 mm., near the surface almost in contact; the vesicles are more numer¬ 
ous than in any other species observed. Cell apertures circular, diameter 
about .25 mm., disposed in irregular intersecting lines, usually distant about 
two-tliirds the diameter of an aperture. Peristomes thin, slightly elevated, 
and having on one side two minute denticulations, which in the course of 
growth form two parallel striations along the inner face of the cell walls. 
Interapertural surface elevated above the peristomes, angular or rounded, 
and occupied by minute, very shallow pits, which frequently appear oval or 
circular, generally one or two series between adjacent apertures, sometimes 
three, especially on or near the monticules. 
When the frond is a little worn or macerated the interapertural surface is 
flattened and the pits have the usual angular form, diameter about .10 mm., 
sometimes even less. Surface marked by obtusely conical monticules, the 
centers of which are distant from each other about 5 mm., with a central 
