BRYOZOA. 633 



other, and given off from one or both sides of the primary set 

 at a very acute angle. At intervals one of the secondary 

 branches becomes thickened and is likewise pinnated. The fenes- 

 trules are sub-quadrate or ovate, generally a little \vider than 

 the branches, with eight or nine in 1 cm. in six of the speci- 

 mens, and between ten and eleven in the seventh. In other re- 

 spects the variety agrees with the typical form. 



Three of the specimens * are from the Chester group of Ken- 

 tucky, three from the Upper Coal Measures of Illinois, and one 

 from the same horizon near Red Oak, Iowa. 



SEPTOPORA PIXXATA Dlrich. 



PL LXTV, fig. 7. PL LXV.flgs, 1-la. 



This form agrees in many respects with S. biserialis, but the 

 pinnate arrangement gives it such a different aspect that it 

 seems unreasonable to regard them as specifically identical. 

 Their relations are about the same as those of S. decipiens to 

 S. subquadrans. In distinguishing it from the var. nervata. we 

 find that the branchlets are given off at a much less acute 

 angle, and that altogether the branches are thinner and the 

 fenestrules comparatively larger. Eight branchlets, averaging 

 0.3 mm. wide, are given off from each side of the midribs, in 

 1 cm. The midribs vary from 0.5 to 0.7 mm. wide. 



Position and locality: Upper Coal Measures, Jasper County, 

 Illinois. 



SEPTOPORA ROBUST A Ulrich. 



PL LVI. fig. 9-9c, and PL LXTV, figs. 3-3a. 



The zoarium of this species is flabellate, and, though with 

 many points of resemblance to S. biserialis, will be immediately 

 distinguished by its more robust appearance, the branches hav- 

 ing an average width of between 0.7 and 0.8 mm., the extremes 

 being 0.6 and 1.1 mm; five to eight branches occur in 1 cm. 

 The dissepiments are either direct or arched, strong, from 0.4 

 to 0.7 mm. wide, and somewhat depressed on the reverse side; 

 the fenestrules vary from circular to transversely oblong sub- 

 quadrate, usually wider than the branches, with seven or eight 

 79 



