EXPLANATION OF PLATE 8 . 1 



i 



1 riplophyllites palmahis Easton, n. sp. ; transverse sections ; X 5 ; Illinois State Geological Sur- ? 



vey specimens p. 35 j 



1, Late ephebic stage ; paratype ; No. 3520. j 



2, Middle ephebic stage ; paratype ; the long septum occupying the cardinal f ossula is a i 

 metaseptum and the cardinal septum is masked by stereoplasm to the right of the I 

 metaseptum ; No. 3521, 



3a-3d, Serial sections of a specimen showing changes in progressively younger 1 

 early ephebic stages ; paratype, destroyed ; the retreat of the septa in the counter 



quadrants is probably a peculiarity and is not of specific value ; the interrupted \ 



cardinal septum is caused by its having an apical sag midway in its length. • 



4a-4c, Serial sections in very early ephebic and late neanic stages; paratype, destroyed; ; 

 the reason for the abnormal development of what appears to be septa in the lower 



left portions of the figures is not known, but is probably related to twisting of the , 



specimen. '; 



5, Section in very late ephebic stage, just above the base of the calyx ; paratype ; reversed ; '\ 

 No. 3522. ? 



6, Ephebic stage showing excessive septal dilation with loculi almost filled with stereo- 1 

 plasm ; even more extensive stereoplasmic thickening is common, but in either case the | 

 septal distribution can only be determined if the median lines of the septa happen to ? 

 be clearly preserved ; paratype ; reversed ; No. 3523. \ 



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