BRYOZOA. 547 



mm. 24 or 25. The measurements of the branches and fenes- 

 trules .in the last are taken from a large and fine example, that 

 shows only the reverse. Fig. 2e, represents a part of one of its 

 branches, and shows the relatively larger fenestrules. The cells 

 were counted on a similar but more typical example. 



In many respects this species resembles F. serratula. Both 

 are abundant and almost constantly associated, showing that 

 they are not local varities of one species. F. teuax has smaller 

 and more numerous branches, as well as smaller fenestrules. 

 Lying side by side, as it often happens, it needs but a glance 

 to discriminate between them. Small fragments of both species 

 resemble the fronds of associated species of Archimedes (particular- 

 ly A. proutana and A. distans,) and it is only by becoming familiar 

 with them through practice that they can be distinguished satis- 

 factorily. 



Position and locality: Warsaw beds, Warsaw, and Monroe 

 Co., 111. Chester group, Chester and Kaskaskia, 111., and Sloan's 

 Valley, Ky. 



FENESTELLA CESTRIENSIS Ulrich. 



PL LI, flgs. 5-5b. 



Zoarium an irregular foliar expansion, 5 or more cms. in 

 length. Branches slender, rather rigid, 0.3 to 0.4 mm. wide, 

 bifurcating at distant though variable intervals, seventeen to 

 twenty in 1 cm., the average, however, being about nineteen. 

 The two faces of the obverse side are rather flat and slope 

 downward rapidly from the sharp cariiia. Dissepiments short, 

 ridge-shaped, about one-half as wide as the branches. Fenes- 

 trules averaging ten in 1cm., the extremes noticed being one 

 more or less, varying from long sub-rectangular to long sub- 

 oval, 0.8 by 0.3 mm. Carina scarcely elevated, when perfect, 

 bearing a row of short spines, usually four in the length of a 

 fenestrule. Zooecia in two alternating ranges, twenty-one or 

 twenty-two in 5 mm., four or five to each fenestrule. On the 

 reverse the branches are narrowly rounded, distinctly striated 

 in the younger or marginal portions of the expansion, with 



