CORALS AND BRYOZOA. 
17 
ten to twelve rows on a branch, separated by prominent serrated ridges, 
which are frequently wider than the cell apertures, often obscuring them. 
Twelve serrations in the space of one mm. 
This species is very common, and when well preserved will be easily recog¬ 
nized, but when so worn or macerated that the longitudinal ridges are obsolete 
it closely resembles T. rhombifera. 
Formation and locality. In the shaly limestone of the Lower Helderberg 
group, near Clarksville, N. Y. 
Trematopora (Orthopora) ovatipora. 
PLATE XI, FIGS 9-11 ; AND PLATE XXIII, FIG. 5. 
Trematopora ovatipora, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 151. 1879. 
“ ? “ “ Report of State Geologist for 1882. Expl. pi. 11, figs. 9-11. 1883. 
Zoarium ramose, solid, very slender; diameter .50 mm. Cell apertures ovate, 
length .30 mm., width about one-third the length ; disposed in longitudinal 
parallel rows: margins slightly elevated, and granulose; at the posterior 
margin of each cell aperture a minute spine ; space between adjacent 
apertures about .15 mm. Five or six rows on each branch, separated by a 
slightly elevated granulose ridge. 
This species may be distinguished from T. regularis by its larger, ovate aper¬ 
tures and the number of rows on a branch. 
Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 
Trematopora (Orthopora) canaliculata. 
PLATE XI, FIG. 1-2 ; AND PLATE XXIII, FIG. 9 
Trematopora canaliculata, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 151. 1879. 
“ ? “ “ Report of State Geologist for 1882. Expl. pi. 11, fig. 12. 1883. 
Zoarium ramose, solid, diameter of branches .90 mm. Cell apertures oval, length 
.25 mm., width from one-half to two-thirds the length; disposed in longitudinal 
parallel rows, alternating: margins distinctly and equally elevated, slightly 
constricting the opening, sometimes having on one side a minute denticula- 
