180 
PALAEONTOLOGY OF NEW YORK. 
This species very nearly resembles some of the forms of Acanthoclema 
Hamiltonense, but there are fewer ranges of apertures on a branch, the longi¬ 
tudinal ridges are stronger, the nodes between the cell apertures are somewhat 
stronger, and there are no evidences of interapertural pits: from the forms 
like Acanthoclema scutulatum having straight ridges, it may be distinguished by 
the stronger ridges, smaller cell apertures and nodes: from Acantholema alter - 
natum, of the Upper Helderberg group, it may be distinguished by its stronger, 
more prominent, longitudinal ridges, and the less prominent nodes between the 
cell apertures: from Trematopora ( Orthopora) hi-spinulata by the much stronger 
and more regular longitudinal ridges. 
Formation and locality. Hamilton group, West Williams, Ontario, Canada. 
Trematopora (Orthopora) tortalinea. 
PLATE LVI, FIG. 9. 
Trematopora tortalinea, Hall. Trans. Albany Institute, vol. x, p. ISO. 1SS1. 
“ “ “ Report of State Geologist for 1SS3, p. 10. 1884. 
Zoarium ramose, solid, growth usually somewhat sinuous, bifurcations infre¬ 
quent; branches frequently diverging at an angle of ninety degrees, diameter 
from .60 to .75 mm Cells tubular, septate, arising from the centre of the 
branch, abruptly curving near the surface, in contact for about two-thirds 
of their length. Cell apertures elongate oval, length .20 mm., width usually 
about one-tliird the length, but sometimes not more than one-fourth, 
disposed in longitudinal rows, which are sometimes regular and parallel, at 
other times somewhat irregular; apertures frequently alternating, forming 
oblique transverse rows; nine or ten longitudinal rows on a branch; 
the surface between them is elevated, forming low, rounded, sinuous or 
twisted ridges; the longitudinal ridges are marked by small nodes or 
granules, giving them a serrated appearance. The cell apertures are indis¬ 
tinct and frequently almost entirely obscured by the ridges. When the 
frond is slightly worn or macerated the longitudinal ridges are indistinct 
or obsolete, and the obliquely transverse disposition of the cell apertures 
is the most conspicuous; the frond in this condition presents a very different 
appearance from that of a well-preserved specimen. 
