EXPLANATION OF PLATE 10 



Figs. 1-7 Triplophyllites exiguus (Miller); plesiotypes p. 40 



i. Transverse section, late ephebic stage; X 5; cardinal septum very short, other majors 

 thin, curved, tending to be withdrawn from center; minor septa short; University of 

 Chicago No. 31633D. 



2, Transverse section, ephebic stage ; X 10 ; detail of dissepiments. 



3, Longitudinal section ; X 5 ; dissepiment shown in upper right portion. 



4, Transverse section, ephebic stage ; X 5 ; dissepiments shown along bottom. 



5, Longitudinal section ; X 5 ; dissepiments shown in left side ; the top edges of 3 and 5 

 fit against the left and right edges of 4 so that the appearance of the dissepiments in 

 transverse and longitudinal section can be seen ; 2-5 are University of Chicago 

 No. 31633B. 



6, Transverse section, early ephebic stage ; X 5 ; septa radial in counter quadrants, pin- 

 nate in cardinal quadrants ; alar f ossulae pronounced ; secondary septa present locally ; 

 University of Chicago No. 31633E, 



7 , Transverse section, late neanic stage ; X 5 ; cardinal septum long ; cardinal fossula 

 large ; alar f ossulae prominent ; secondary septa lacking ; University of Chicago 

 No. 31632. 



78 



