CORALS AND BRYOZOA. 
285 
Formation and locality. Hamilton group, Western New York. Particular 
locality not recorded. 
Ptilopora nodosa. 
PLATE LXVI, FIG. 25. 
Ptilopora nodosa, Hall. Trans. Albany Institute, vol. x, p. 196. 1881. 
“ “ “ Report of State Geologist for 18S3, p. 59. 1884. 
Zoarium consisting of a stipe or midrib proceeding from a spreading base 
attached to other organic bodies, and having equidistant lateral branches, 
connected by dissepiments. On the fragments observed the stipe is 
about .33 mm. in width, essentially uniform in size ; transverse section 
circular or broadly oval ; lateral branches about .20 mm. in width, regularly 
distant more than twice the width of a branch, eight or nine in the space of 
5 mm., diverging from the midrib at an angle of about seventy-five degrees. 
On the non-celluliferous face the midrib and lateral branches are convex, 
and finely striated. Dissepiments abruptly rounded, finely striated, depressed 
below the plane of the branches and scarcely expanding at their junction, 
usually occurring at intervals of about 1 mm. or a little less. 
On the celluliferous face the midrib is of about the same convexity as on 
the opposite face; the lateral branches are more abruptly convex; midrib 
finely striated, and with a row of comparatively prominent equidistant 
nodes along the middle, about eleven in the space of 5 mm. Cell aper¬ 
tures oval, in two ranges, opening laterally; looking directly upon the midrib 
they are scarcely distinguishable, on the branches they are more conspicuous ; 
separated by about two-thirds the length of an aperture, fifteen in the space 
of 5 mm. Peristomes thin, distinctly and equally elevated. There is a row 
of nodes along the middle of the branches, smaller and more closely disposed 
than those on the midrib. Dissepiments sharply rounded, striated, much 
depressed below the plane of the branches. 
Jl U At. AL 
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Formation and locality. Hamilton group, Railroad cutting, two and one-half 
miles east of Alden station, Erie county, N. Y. 
