BRYOZOA. 529 



hexagonal in outline, smallest in the central rows, gradual^ in- 

 creasing in size toward the rather wide, punctate or finely 

 striate margin. 



Position and locality; Keokuk group: Keokuk, Iowa: Xauvoo, 

 Warsaw and other localities in Illinois. A common and charac- 

 teristic species. 



var. BURLINGTONENSIS Ulrich. 



PL LXVH. Fig. 2-2b. 



The two specimens figured are from the Burlington limestone 

 at Burlington, Iowa, and agree very closely with the T. ramu- 

 losa, but are somewhat more robust. The cell apertures appear 

 to have been a little more circular and the sloping areas sur- 

 rounding them are never confluent so far as observed. The 

 material is not in condition to furnish good thin sections, so 

 that the internal characters could not be compared. One speci- 

 men is an anastomosing form and may not belong here. 



T.ENIODICTYA FRONDOSA Ulrich. 

 PL LXVH, Fig. 5. and PL LXIX, Fig. 5-oc. 



Zoarium an expanded frond, a cm. or more in height and width, 

 and one-half mm. or more in thickness. Surface nearly even, 

 marked with clusters, something more than their own diameter 

 (1.5 mm.) apart composed of larger sized cells. At the center of 

 the clusters is often found a greater or less aggregation of 

 small openings (mesopores?). Cell apertures in more or less reg- 

 ular, diagonally intersecting series, sub-circular, with moder- 

 ately thick interspaces, seven or eight of the average size in 2 

 mm., those in the clusters from one-third to one-half larger 

 than the others. Inter-apertural spaces ridge-like, witli the 

 central portion sub-angular, and when in a good state of pres- 

 ervation bearing minute granules. Zooecia prostrate, the ves- 

 tibule almost direct to the surface. In a tangential section the 

 space along the middle of the zooecial partitions exhibits a large 



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