NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
643 
The tergopores have so far been observed only in the genera Mesonea and 
Pleuronea. 
Firmatopores. — The firmatopores (=canal of reenforcement of Pergens) are 
longitudinal, cylindrical, capillary tubes on the dorsal of the zoarium. They 
arise on the basal lamella at all heights and are directed toward the base in the 
opposite direction to the zooecia which are ascending; they form by their opening 
on the substratum, the basal system of fixation of the zoarium (fig. 203). 
Longitudinal tliin section, X 
25, of Diplodesmopora oppo- 
site new genus and species 
from the Coniacian at Tours, 
France, showing zooecial tubes 
to right and nematopores to 
left. 
B x 1 2 
Fig. 205. — Dactyletlirae. 
A. Longitudinal thin section of Erlcosonca 
semota new species, X 25, showing dactyle- 
thrae (to right) and zooecial tubes. B. Dorsal 
of the same species, X 12, illustrating dactyl e- 
thrae closed by a lamella. C. Longitudinal 
thin section of Clausa heteropora D’Orbigny, 
showing dactyletlirae (to right) and zooecial 
tubes. 
Nematopores. — The nematopores are inferior and opposite ramifications of 
the oriented tubes; they are always rectilinear and their orifice is oblique. Their 
walls are thin or thick, but always adjacent. They are sometimes closed by a 
calcareous epitheca (fig. 204). They are distinguished from firmatopores, which 
have the same threadlike aspect, in their ascending and not descending arrange- 
ment. 
