BKYOZOA. 553 



trule, so arranged that one is opposite each dissepiment and 

 one between. Opercular covers the same as those of the F. 

 sevillensis, F. wortheni, F. rudis, and many other species. 



This species is closely related to F. tenax, of the Warsaw and 

 Chester beds, but is more delicate, has larger cell apertures and 

 fenestrules and a smaller number of branches in a given space. 

 F. sevillensis is larger, has longer fenestrules, fewer cells, and 

 an impressed mesial line instead of a keel. F. wortheni differs 

 in its remarkably developed keel. 



Position and locality: Coal Measures. Seville, 111. 



FENESTELLA CONRADI Ulrich. 



1 PL LH, figs. 8, 8a. 



Zoarium a strongly undulated foliar expansion, several cm. 

 in length. Branches strong, appearing very rough on their ob- 

 verse side, about 0.4 mm. wide, with twenty-one or twenty-two 

 in 1 cm. Dissepiments very short and broad. Fenestrules nar- 

 row, sub-elliptical, averaging 0.33 by 0.15 mm., sixteen or sev- 

 enteen in one cm., arranged in diagonally intersecting series. 

 Carina itself not much elevated, but the rather closely arranged 

 compressed spines which it bears are very strong and exception- 

 ally prominent when perfect. Their bases are often in contact 

 when they form a sort of rough crest. Zooecia in two ranges. 

 Apertures circular, with slight peristome, arranged in a not 

 very straight line, so that there are several times three to once 

 two in the space of a fenestrule; twenty-three in 5 mm. On 

 the reverse the branches and dissepiments are rounded, on the 

 same plane and about equally thick, the former being thinner 

 than on the obverse side. The fenestrules are almost perfectly 

 circular. A small node, perforated at its summit, often occupies 

 then center of the branch at a point midway between four 

 ad j acent fenestrules . 



The circular fenestrules and other features of the reverse, and 

 the strong spines on the keel, (they are more conspicuous than 

 in fig. 8,) are relied upon in separating this species. The ob- 

 verse brings F. rudis to mind, but that species is so much 

 more robust that comparisons are unnecessary. 



69 



