BRTOZOA. 543 



mm. Carina strong, cord-like, carrying strong nodes about 0.7 

 mm. apart. Zo<ecia in two alternating ranges. Apertures oc- 

 cupying a groove at the base of the carina, thirteen in 5 mm., 

 usually sub-circular, with only the outer margin strongly ele- 

 vated; often they appear slit-like, an appearance probably due 

 to compression; from four to six or even more between suc- 

 ceeding dissepiments. Reverse not seen. 



This species is less robust and more irregular than F. regalis. 

 F. filistriata of the Burlington limestone, is more delicate and 

 without the cord-like keel. 



Position and locality: Keokuk group. Rare at Keokuk, Iowa. 



FEXESTELLA CINGVLATA Ulrich. 



PI. EH, flgs. l-ld. 



Zoarium a large and strong, flat, foliar expansion, the larg- 

 est fragments at hand indicating a diameter of at least 8 em. 

 Branches strong, equal, about 0.5 mm. wide, rigid, bifurcating 

 at long intervals: fifteen in 1 cm. Dissepiments strong, gener- 

 ally two thirds as wide as the branches, usually elevated node- 

 like, a peculiarity particularly noticeable on weathered exam- 

 ples, giving them a very characteristic rough appearance. Fen- 

 estrules narrow, indented by the cell margins, about 0.8 mm. 

 in length, and 0.15 to 0.25 mm. in width, eight or eight and 

 one-half in 1 cm. Cariiia not well developed but bearing con- 

 spicuous nodes. Zoo?cia in two alternating ranges. Apertures 

 circular. 0.15 mm. in diameter, with strong peristome, about 

 seven to two fenest rules and fifteen to sixteen in 5 mm. The 

 opercular covers to the apertures are frequently preserved. 

 Tangential sections taken close to the surface show the exist- 

 ence of a ring of exceedingly minute vertical pores around the 

 zooecia aperture. Under a high power these appear on the sur- 

 face of the peristome as minute granules. On the reverse the 

 branches are simply convex and narrower, the fenestrules larger 

 and more regular in size and shape, while the dissepiments are 

 about as wide as the branches, and on the same plane with 

 them. Their surface is crowded with minute granules, which 

 only on very young examples are arranged in longitudinal 



