EASTMAN: CARBONIFEROUS SHARKS. 



75 



with increase in the number of segments. A divergent series, how- 

 ever, is represented by the species of Edestus, in which the relatively- 

 few se'^ments are not very intimately fused, while their coronal por- 

 tions become reduced pari passu with the enormous development of the 

 base. In fact, about all th/ remains of the crown in Edestus is the 



Fig. 6. 



Cross-sections of symphysial teeth of Edestus. A, Type of E. heinrichi N. & W. 

 X \- B, Type of E. vorax Leidy (after Leidy). X \. C, Type of E. giganteus 

 Newb., taken vertically tlirough the penultimate tooth of the series. X 2- 



apical portion, the two processes corresponding to the buttressed lateral 

 faces of Campodus appearing as slender prolongations (cf. text-fig. 7). 

 The relative compression amongst these various forms is apparent from 

 their cross-sections, of which figures are given herewith. It will be 



