BRYOZOA. 439 



STENOPORA INTERCALARIS Ulrich. 



PL LXXIY, Fig. 5-5a. 



Zoariura consisting of large cylindrical branches from one to 

 two cm. in diameter. Surface smooth, without groups of larger 

 cells. Zooecia polygonal, somewhat variable in size, apertures 

 subangular, 0.18 to 0.25 mm. in diameter, about ten in three 

 mm. Interspaces moderately thick, with spines at the angles 

 when the surface is well preserved. Walls of zooecia thin and 

 faintly flexuous in the axial region, thickened and irregularly 

 moniliform in the cortical region, the beads not separated by 

 thin intervals, but merged into each other. Mesopores quite 

 numerous for the genus, small, but varying in size, circular or 

 angular, intermittent and irregular. A few diaphragms developed 

 in the outer part of the axial region, generally^ absent in the 

 cortical region. Acanthopores numerous, invariably situated at 

 the angles of junction. 



This species differs from S. americana, with which it is asso- 

 ciated, in having no monticules nor clusters of large cells, 

 smaller cell apertures, far greater number of mesopores (which 

 may be detected on the surface) and much fewer diaphragms. 



Position and locality: Keokuk group, Warsaw, HI. 



STENOPORA AXGULARIS Ulrich. 



PI. LXXIV, Fig. 6-6b. 



Zoarium consisting of extremely massive branches, the largest 

 specimen under investigation being eight cm. wide and four cm. 

 thick just before a bifurcation, the latter measurement being 

 about equivalent to the normal diameter of the branches. Sur- 

 face smooth but with group of cells decidedly larger than the 

 average. Apertures angular, variable in form, with thin inter- 

 spaces, about ten in three mm. Walls of tubes thin in the axial 

 region, and but very little thickened in the cortical though pre- 

 serving the moniliform character of the genus. In the cortical 

 region the zocecia do not form continuous tubes, but the whole 

 is divisible into a number of distinct thin Ia3^ers. Mesopores 

 very few. Diaphragms wanting. Acanthopores abundant and 

 commonly occupying the angles, not very large, but conspicuous 

 on account of the tenuitv of the walls. 



