624 PALEONTOLOGY OF ILLINOIS. 



more widely separated large openings beneath them. The latter 

 represent the broken branches. 



Reverse. Midrib prominent, subcylindrical, from 0.6 to 0.8 

 mm. wide, and like the branches finely striated. Branches sub- 

 cylindrical, rigid, 0.3 to 0.4 mm. wide, twelve to fourteen given 

 off from the midrib, at an angle of about 65 in 1 cm. Dissep- 

 iments easily overlooked, depressed, very thin, two or three in 

 number, about 1.1 mm. apart. Fenestrules narrower than the 

 branches. 



Obverse. Midrib with a more or less defined, low, rounded, 

 central ridge, carrying a row of small hollow nodes, 0.4 mm. 

 apart, and, in the younger stages, with a fine line on each side. 

 In old examples the whole space between the ranges of aper- 

 tures is almost uniformly rounded, but without obliterating the 

 nodes. The surface of the branches is simple rounded, but a 

 similar row of small nodes runs along the center. Zocecia in 

 two ranges. Apertures submarginal, very small, circular or sub- 

 oval, with prominent but not abruptly elevated peristome, 

 thirteen or fourteen in 5 mm. on both midrib and branches. On 

 the former they are situated one at the base of each branch 

 and one midway between. 



When found in shale, the substance of the zoarium has a 

 polished aspect that is not shared by any of the associated 

 Bryozoa. 



This species, like P. valida, might easily be mistaken for 

 Pinnatopora, and, indeed, I believe that the short branches and 

 thin dissepiments of these two forms, point to a clear relation- 

 ship with species of that genus. 



Position and locality: Keokuk group, King's Mountain, Ky., 

 and Bentonsport, Iowa. The examples from the last locality 

 have the branches slightly wider apart than the Kentucky 

 specimens. The last being the most perfect and numerous, are 

 considered as the most typical. 



PTILOPORA PAUPER A Ulrich. 



PI. LXVI, Fig. 10. 



Zoarium a small, rather irregularly pinnate frond, with the 

 hight and width about equal. Midrib and branches strong and 



