CORALS AND BRYOZOA. 29 



The ch<aracteristics 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. 



FiSTOLIPORA 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 t» 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. 



