536 PALAEONTOLOGY OF ILLINOIS. 



space of 1 cm. Carina rarely prominent, it and the sides of 

 the branches covered with fine longitudinal striae. Zooecia in 

 two ranges. Apertures circular, elevated, almost twice their 

 diameter apart, six or seven to a fenestrule, thirteen or four- 

 teen in 5 mm. On the reverse the branches are striated longi- 

 tudinally as on the obverse. 



This species is much more delicate than the F. regalis of the 

 Keokuk group. F. funicula, has a stronger keel, and no striae 

 upon the obverse. 



Position and locality: Burlington limestone, Burlington, Iowa, 

 and Montezuma, Pike Co., 111. 



FENESTELLA BURLINGTONENSIS Ulrich. 



PI. SLIX, fig. I, la. 



Zoarium a foliate expansion, with strong root-like processes 

 extending from the sides near the base. Branches rather strong, 

 a little irregular, from 0.3 to 0.5 mm. wide. Dissepiments short, 

 rounded or subangular, depressed, from one-half to two-thirds 

 the width of the branches. Fenestrules irregular in shape and 

 size, varying from subquadrangular to narrow elliptical, aver- 

 aging 0.7 by 0.4 mm., with eight to ten in 1 cm. Carina 

 strong, moderately elevated and bearing a row of obscure 

 nodes. Zooecia in two ranges. Apertures circular, small, widely 

 separated, about seventeen in 1 cm., and from three to five to 

 each fenestrule. On the reverse the dissepiments are more slen- 

 der and fenestrules more rectangular than on the obverse. On 

 the branches are a few obscure nodes. 



The Burlington Bryozoa are rarely good, and the examples 

 of this Fenestella, which I have seen are no exception to the 

 rule. They show perhaps too great a variation to have all 

 belonged to one species, yet as the state of preservation did 

 not admit of nice discriminations, I thought it best to unite 

 provisionally the forms comprised in the above description 

 under one name. The example of which fig. la, represents a 

 small portion has smaller and more crowded branches than 

 usual. The species is related to F. rudis of the Keokuk group, 

 but has smaller cell apertures and somewhat larger fenestrules. 



Position and locality: Burlington limestone. Burlington, la. 



