EXPLANATION OF PLATE 9 



Figs. 1, 2 Triplophyllites centralis (Milne-Edwards and Haime) ; plesiotypes ; x5 ... p. 39 



1, Transverse section, ephebic stage ; cardinal septum short ; septa more radial in arrange- 

 ment ; alar fossula barely discernable ; septa of counter quadrants withdrawn from 

 central area ; after Grove. 



2, Transverse section, neanic stage ; long thickened cardinal septum extends to stereo- 

 theca ; septa of cardinal quadrants extend to wall ; septa of counter quadrants abut 

 against alar septa ; dissepiments sparse ; after Grove. 



Figs. 3-5 Triplophyllites cliff or danus (Milne-Edwards and Haime) ; plesiotypes ; X 5 . . . p. 39 



3, Transverse section, ephebic stage ; section ovate, cardinal septum long ; median lines 

 of septa shown because of obscuring effect of stereoplasmic thickening of septa ; State 

 University of Iowa No. 9902. 



4, Pattern of septal grooves as seen in three dimensions when looking down upon apex 

 of corallite. 



5, Pattern of septal grooves when seen from side ; 4 and 5 are from the same specimen : 

 State University of Iowa No. 9902. 



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