PLATE LII. 



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PAGE 



Fig. 1. FENESTELLA CINGULATA Ulr 543 



1. Obverse surface, x9, of the best specimen seen. In manv the dissepi- 

 ments are more elevated. 



1 o. Reverse of a variety of this species having longer fencstrules than 

 usual, x9. 



1 ft. Thin section, x!8, showing structure just beneath the zooe 'ia aper- 

 ture. 



1 c. One of the zooecia of flg. 1 b, x50, to show the ring of minute tubes. 



1 '/. Another portion of same section where it passes through the zoarium 

 near the reverse face, x!8. 

 Keokuk group, Nauvoo, 111. 

 E. 0. Ulrich's collection. 



Fig. 2. FENESTELLA DELICATULA Ulr 549 



Fragment of this species showing the obverse side, x9. 

 Lower Coal Measures, Seville, 111. 

 Illinois State Museum. 



Fit'. 3. FENESTELLA MODESTA Ulr 550 



3. Portion of a gutta-percha cast,x9. 



3 a. One branch of fig. 3 more highly magnified, x!8. 



3 li. From a gutta-percha cast of a fragment showing reverse, x9. 



Lower Coal Measures, Knox Co., III. 

 Illinois State Museum. 



FJK. 4. FENESTELLA PEKMINUTA Ulr 551 



4. A small almost complete specimen, x9. 



1 a. Same, x18, showing the faint carina, and the projecting Izooocia. 



4 6. One branch of another specimen showing the reverse, x!8. 



Lower Coal Measures, Seville, 111. 

 Illinois State Museum. 



Fig. 5. FKNESTELLA WOKTHENI Ulr 551 



5. Portion of a specimen showing the obverse side, x9. 



5 a. A branch and row of fenestrules of flg. 5, more highly magnified to 



show more clearly the peculiar keel with its row of minute pores, 



x!8. 



Lower Coal Measures, Seville, 111. 



Illinois State Museum. 



Fig. 6. FENESTELLA SEVILLENSIS Ulr 552 



6. Portion of a fragment, x9. 



6 a. One branch, x!8, to show the peculiarities of the cells and keel. 

 6 b. Reverse, x!8. 



Lower Coal Measures, Seville, 111. 

 Illinois State Museum. 



