BRYOZOA. 673 



In this specimen the interspaces are long and narrow. It is 

 from the base of the "Warsaw beds, at Warsaw, 111. 

 No. 3. Transversely. 7.5 apertures in 3 mm. 



Sixteen of the transverse rows in 3 mm. 

 Diagonally, 12 apertures in 3 mm. 

 Total number in 3 mm. square, 120. 



In this specimen the interspaces are wider and shorter than 

 usual. Its surface is represented by figs. 3-3b. Keokuk group, 

 Xauvoo. 111. 



Position and locality: A common species in the Keokuk and 

 Warsaw beds at mam- localities in Illinois and Iowa. 



CYCLOPORA EXPATIATA Ulrich. 



PL LXVm, fig. 4-4d. 



Zoarium a very large unilaminar expansion, from 0.5 to 1 

 mm. thick; one specimen before me (incomplete) has a breadth 

 of 15 cms. and a width of 8 cms.; occasionally incrusting, 

 usually free, with the under surface protected by an epithecal 

 membrane more or less~rugosely wrinkled in an irregularly con- 

 centric manner. The wrinkles are crossed by faint radiating 

 lines. Surface with scarcely elevated monticules, composed of 

 small aggregations of mesopores and a few zooecia of larger 

 size than the average. Zooecia apertures subcircular, 0.2 mm. 

 in diameter, not very regularly arranged, ten or eleven in 3 

 mm., often completely isolated by the large, irregularly shaped 

 mesopores, but usually in contact with each other at one or 

 more points. A thin peristome, carrying from four to eight 

 nodes (?acanthopores) surrounds the apertures. In thin sections 

 the walls are thin and exhibit considerable variability of struc- 

 ture, probably indicative of developmental stages, the sequence 

 of which has not been determined. Sometimes the transversely 

 lined structure shown in fig. 3e, PI. LXVIII, is quite distinct, but 

 usually the appearance is more like whatsis shown by figs. 4-4c 

 of the same plate. Several diaphragms intersect the zooecial 

 tubes in vertical sections. 



This species differs from C. fungia,, in the larger size of the ex- 

 pansion, the well developed acanthopores, and less regular ar- 

 rangement of the zocpcia. Tangential sections of the two look 

 quite different. 

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