CORALS AND BRYOZOA. 
213 
diameter about .25 mm., irregularly disposed, generally distant from each 
other a little more than their diameter. Peristomes strong, equally elevated, 
granulose when well preserved. Mesopores large, frequently equal in size to 
the cell apertures; margins elevated slightly less than the peristomes. Sur¬ 
face marked by sterile maculae of 1 to 2 mm in diameter, occurring at ir¬ 
regular intervals, the cell apertures immediately adjacent not larger than the 
others. 
The characteristics of this species are the absence of monticules and the 
comparatively distant cell apertures. It may be distinguished from F. serrulata 
which it resembles in size and frequency of the cell apertures, by the absence 
of monticules and conspicuous opercula: from F. variapora and F. confertipora 
by the absence of monticules and by its large mesopores. 
Formation and localities. Hamilton group, Eighteen-Mile creek, Erie county, 
and Bellona, Yates county, N. Y. 
Fistulipora umbilicata. 
NOT FIGURED. 
Thallostigma umbilicata , Hall. Trans. Albany Institute, vol. x, p. 185. 18S1. 
“ “ “ Report of State Geologist for 1883, p. 22. 1884. 
Zoarium consisting of free or incrusting lamellate expansions, or of masses 
formed by the superimposition of successive layers of growth; greatest 
thickness of the fronds observed 1.50 mm.; under surface consisting of an 
epitheca with strong concentric wrinkles. Cells tubular, cylindrical, 
rectangular or slightly oblique to the surface, usually opening directly 
outward. Intercellular space vesiculose; near the base the vesicles are 
irregularly disposed, above they are regularly superimposed. Cell apertures 
circular, diameter about .30 mm., irregularly disposed, usually distant about 
three-fourths the diameter of an aperture. Peristomes strong, equally 
elevated, smooth. Mesopores variable in size, sometimes minute, at other 
times nearly as large as the cell apertures; margins slightly elevated, some¬ 
times continuing upon the peristomes and giving them a strongly striated 
appearance. Surface marked by broad, rounded monticules, the centers of 
