CORALS AND BRYOZOA. 
29 
The characteristics of this species are the very irregular arrangement of the 
cell apertures, and the large and numerous mesopores. The ramose forms may 
be distinguished from Callopora, cellulosa by the much larger and more numerous 
mesopores and the hollow branches; from Callopora venusta by the smaller and 
more distant cell apertures and the larger and more numerous mesopores. 
Formation and locality In the shaly limestone of the Lower Helderberg 
group, near Clarksville, N. Y. 
Fistulipora triloba, n. sp. 
NOT FIGURED. 
Zoarium generally explanate, sometimes ramose, branches hollow, of very 
irregular growth, undulating or contorted; often massive from the super¬ 
imposition of successive layers of growth. Thickness of fronds (?) varying 
from 1 to 5 mm. Under surface consisting of a thin, concentrically wrinkled 
epitheca. Cells tubular, arising from the epitheca, and almost immediately 
assuming an erect position, and thus continuing to the surface ; walls very 
thin. Septa infrequent or entirely wanting. Apertures sub-triangular or 
trilobate, length .30 mm., greatest width .25 mm., or slightly more; irregu¬ 
larly disposed ; space between adjacent apertures less than the length of an 
aperture : margins elevated, sometimes equally, at other times the posterior 
is the most strongly elevated. At a little less than half the distance from 
the posterior end there are two dentations, which give to the apertures the 
trilobate form, and which in the course of growth form two fine striations on 
the interior of the cell-wall. Mesopores minute, from one to three series 
between adjacent apertures. Surface marked by maculae destitute of cell 
apertures, the centers of which are distant from each other about five mm. ; 
the apertures immediately adjacent are larger than the others and radiate 
from the maculae. Intercellular space occupied by septate tubuli, except 
near the base of the cells, where the structure is irregularly vesicular. From 
eight to ten septa in the space of one mm. On one specimen the margins of 
the apertures are very much elevated, thickened and in many cases closed. 
Formation and locality. Lower Helderberg group, near Schoharie, N. Y. 
