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 segments are not very intimately fused, while their coronal por- 
tions become reduced part passu with the enormous development of the 
base. In fact, about all the remains of the crown in Edestus is the 
A\ 
a 
\ 
a B. C. 
Fie. 6. 
Cross-sections of symphysial teeth of Edestus. A, Type of EL. heinrichi N. & W. 
x}. B, Type of EL. vorax Leidy (after Leidy). x $~. C, Type of E. giganteus 
Newb., taken vertically through the penultimate tooth of the series. X 3. 
apical portion, the two processes corresponding to the buttressed lateral 
faces of Campodus appearing as slender prolongations (ef. 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 
