CORALS AND BRYOZOA. 
181 
This species most nearly resembles T. (0.) lineata of this geological forma¬ 
tion, and T. ( 0 .) regularis of the Lower and Upper Helderberg groups ; the 
diameter of the branches is about the same, but it may be distinguished by the 
disposition of the cell apertures in sinuous, longitudinal rows; the ridges 
separating them are much less prominent than those of the other species; the 
whole appearance of the frond is much more irregular: when those species are 
worn or macerated the longitudinal disposition of the cell apertures remains 
the most conspicuous. From Acanthoclema sulcatum it is distinguished by the 
low, rounded ridges, the greater number of rows of apertures, and its more 
irregular appearance. When worn or macerated it is similar to T. (0.) rhombi- 
fera of the Lower and Upper Helderberg groups, but the cell apertures are 
surrounded by low, broad ridges, and not situated in a vestibular area as in 
that species; it has also a close resemblance to a macerated condition of 
Acanthoclema Hamiltonense. 
Formation and locality. Hamilton group, Hamburg-on-the-Lake, Erie county, 
New York. 
Trematopora (Orthopora) lineata, n. sp. 
PLATE LV, FIGS. 3-8; and PLATE LVI, FIG. 10. 
Zoarium ramose, solid; bifurcations infrequent; branches often diverging at 
an angle of ninety degrees, diameter about .GO mm. Cells tubular, arising 
from the center of the branch, oblique to the axis, in contact for about two- 
thirds their length, abruptly bending outward near the surface. The arrange¬ 
ment of the cells is obscurely similar to Acanthoclema. Cell apertures 
elongate-oval, length .18 mm., width about one-third the length, distant, 
disposed in longitudinal, parallel rows, eight or nine rows on a branch, 
apertures longitudinally distant a little more than their length. Peristomes 
very thin, scarcely elevated. Rows separated by prominent, grannlose ridges, 
which present a minutely serrated appearance, intermediate surface smooth. 
The granules on the ridges, in the course of growth, form very minute tubuli 
between the cells. 
