184 
PALEONTOLOGY OF NEW YORK. 
little less than one-half the length; sometimes irregularly disposed, but usually 
in longitudinal rows, alternating and forming oblique transverse rows, the 
two arrangements being equally conspicuous. The peristomes are usually 
very slight or obsolete, the intermediate space hat or convex, the apertures 
appearing immersed; sometimes the peristomes are comparatively strong 
and the intermediate space slightly concave, the surface often presenting a 
confused appearance. The surface is nodose, nodes sometimes irregularly 
disposed, at other times there is a single row between adjacent apertures, 
usually surrounding the aperture, but sometimes disposed in straight lines, 
resembling ridges, and frequently partially obscuring the cell apertures. In 
the process of growth these nodes form minute tubuli between the cells. When 
the frond is worn or macerated the nodes are partially obliterated and the cell 
apertures are much more conspicuous than in a perfectly preserved specimen. 
This species most nearly resembles T. (0.) transversa, and it will sometimes 
require a careful examination to distinguish them, but the branches are more 
slender, and the cell apertures more elongate-oval. Internally the cell tubes 
are not regularly curved. From T. (0.) interplana it may be distinguished by 
its more elongate-oval cell apertures and their closer disposition. From other 
species of this geological formation it is distinguished by its elongate cell aper¬ 
tures, generally surrounded by a row of comparatively prominent nodes. 
Formation and localities. Hamilton group, near Canandaigua Lake, and shore 
of Owasco Lake, N. Y. 
Trematopora (Orthopora) ornata, n. sp. 
PLATE LV, FIG. 1 ; and PLATE LVI, FIG. 4. 
Zoarium ramose, solid; branches 1 mm. in diameter. Cells tubular, arising 
from the centre of the branch. Cell apertures oval, length about .20 mm., 
width a little less than one-half the length, disposed in longitudinal, parallel 
rows, alternating and forming oblique transverse rows, at an angle of forty- 
tive degrees to the axis of the branch. Peristomes very thin, scarcely 
elevated. Surface between the apertures elevated, obtusely angular, and 
with numerous irregularly disposed nodes. 
