CORALS AND BRYOZOA. 285 



Formation and locality. Hamilton group, Western New York. Particular 

 locality not recorded. 



Ptilopora nodosa. 



PLATE LXVI, FIG. 25. 



Ptilttpora nodosa. Hall. Ti-ans. Albany Institute, vol. x, p. 196. 1881. 



Report of State Geologist for 1883, 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 later.al 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 morie closely disposed 

 than those on the midrib. Dissepiments sharply rounded, striated, much 

 depressed below the plane of the branches. 



Formation and locality. Hamilton group, Railroad cutting, two and one-half 

 miles east of Alden station, Erie county, N. Y. 



