PLATE XLIX. 



PAOI. 



Fig. 1. FENESTELLA BUKLINOTONENSIS Ub- 636 



1. Obverse face of a frond showing the usual characters of the species. x9. 



1 a. Obverse side of another specimen having thinner branches and morn 

 elongate fenestrules, x9. 

 Burlington limestone, Burlington, Iowa. 

 Illinois State Museum. 



fig. 2. FENESTELLA FILISTBIATA Ulr 536 



2. Several branches showing the fine stria; and distribution of the zonscia 



apertures, x9. 



2 a. The reverse face of a "frond" showing the relative size of the branches 

 and fenestrules, x9. Nearer the base the branches are comparatively a 

 little stronger. 



Burlington limestone, Burlington, Iowa. 

 Illinois State Museum. 



Fig. '(. FENESTELLA RUDIS Ulr 537 



3. Obverse face of a frond, x9, showing the characters of the branches and 



other features of the species near the base. 



Bentonsport, Iowa. Keokuk group. 



Illinois State Museum. 

 3 n. Reverse aspect of another specimen showing the subnodose character 



of the branches, x9. 

 3 b. Obverse side of a line specimen showing the appearance of the frond 



toward the upper margin. Also several of the supposed ooacia, x9. 



Keokuk group. Warsaw, 111. 



Illinois State Museum. 



3 c. Portion of fig. 3 b, x!8, to show the tine striations, compressed tuber- 

 cles, and the opercular covers. 



3 (/. A small portion of the reverse of a well preserved example, showing 



irregular nodes. 



Keokuk group, Nauvoo, 111. 



E. O, Ulrich's collection. 



Fig. 4. FENESTELLA LIMITABIB, Ulr 538 



4. Obverse face, x9, showing the relative size of the branches and fenes- 



trules, the obsolete carina. and the rather large and regularly alternat- 

 ing zooecia apertures. 



4 a. Reverse of same specimen, but from another portion where the branches. 



are more rigid, x9. 



Keokuk group, Bentonsport, Iowa, 



Illinois State Museum. 



