BRYOZOA. 519 



pressed, sometimes even occupying the summits of broad eleva- 

 tions. The zon-cia apertures are direct and sub-circular in out- 

 line, with the lunarial side usually somewhat straightened and 

 pinched in the middle,the peristome thinner and sub-equally 

 elevated, the apertures considerably larger, those of the average 

 size being about 0.25 mm. in diameter, while some of those in 

 the immediate vicinity of the maculae are frequently 0.4 mm. in 

 width. Nine and one-half or ten of the ordinary zocecia aper- 

 tures occur in 5 mm, At the junction of the leaves they are 

 somewhat thickened and there is no narrow depressed non- 

 poriferous strip at the line of junction. The interspaces and 

 macula? appear rather coarsely granular or pitted at the surface. 

 Internally they are occupied by larger and fewer vesicles. These 

 differences seem amply sufficient to distinguish the two species. 

 A nearer congener is probably found in G. pinnata of the Bur- 

 lington limestone. 



Position and locality: Keokuk group. Occurs at Warsaw and 

 Nauvoo in 111., and Keokuk and Bentoiisport in Iowa. 



GLYPTOPORA PUNCTIPORA Ulrich. 



PI. LXXVUI, Fig. 9-9a. 



In the manner of growth and general aspect this species is 

 precisely like G. keyserlingi, and G. elegans, with the single ex- 

 ception that the maculae or dimples are smaller, and very little 

 impressed, usually appearing on a level with the general plane 

 of the surface. They are consequently a much less conspicuous 

 superficial feature than in those species. The zooecial apertures 

 are small, compressed, somewhat kidney-shaped, the longer 

 diameter about 0.2 mm.; arranged in regular curved diagonally 

 intersecting series, 11 or 12 in five mm. The apertures occupy 

 the summits of rounded confluent pustules, which are a little 

 the largest in the vicinity of the maculae. The width of the 

 interspaces usually equals about one and a half times the long 

 diameter of the apertures. In sections the zooecia are thin- 

 walled, the lunarium fairly distinct, the vesicles numerous and 

 generally in two series between the zooecia. Several sections 

 show very plainly the minute perforation in the vesicle covers. 



