548 PALAEONTOLOGY OF ILLINOIS. 



irregularly distributed nodes and no striations toward the basal 

 or older parts. The fenestrules are more nearly rectangular 

 than Jon the obverse. 



This graceful species is one of the most characteristic Bryo- 

 zoa of the Chester group. Although in no case very abundant 

 it occurs at all the typical localities. In its measurements the 

 the species agrees quite closely with F. flexuosa,, yet the two are 

 not likely to be confounded. 



Position and locality: Chester group, Chester, Kaskaskia, 

 near Anna, and other localities in the State of Illinois. Also 

 at Sloan's Valley, and Litchfield, Ky. 



FENESTELLA FLEXUOSA Ulrich. 



PI. LI, figs. 4 4c. 



Zoarium a somewhat undulating foliaceous expansion that 

 probably did not exceed 5 or 6 cms. in diameter. Branches 

 slender, 0.3 to 0.35 mm. wide, rather irregularly flexuous, alter- 

 nately bending toward and away from one another, eighteen to 

 twenty in 1 cm. Dissepiments very short, connecting the 

 branches where they approach each other nearest, their width 

 about equal to that of the branches. Fenestrules long-oval, 

 more or less pointed at the ends, somewhat variable as to size, 

 about 0.8 by 0.2 mm., and nine or nine and one-half in 1 cm. 

 Carina rather strong, moderately elevated, with generallv three 

 strong nodes or spines to the fenestrule. Zocecia in two ranges 

 about twenty-two in 5 mm. Apertures circular, their diameter 

 or less apart, four or five to each fenestrule, with well developed 

 peristome. On the reverse the branches are very finely granu- 

 lo-striate or smooth, narrowly rounded or carinated, and on 

 account of their zigzag direction, usually apper to inosculate. 

 The fenestrules are a little longer than on the opposite side, 

 elliptical, but somewhat variable both in shape and size. 



This is a well marked form, and ought never to be confounded 

 with any other Carboniferous species known. 



Position and locality: Chester group. Not uncommon at 

 Sloan's Valley, Ky.,? Chester, 111. 



