﻿ICHTIIY0D0RULITK3. 



Pig. 11. 



151 



Harpacanthus fimbriatm (Stock). — M. Carb. Limest., Gilmeiton. (After 

 Traquair. ) 



Y. Dermal defences of doubtful position. 



Genus EDESTUS, Leidy. 



[Proc. Acad. Nat. Sci. Philad. vol. vii. 1856, p. 414.] 



Syn. Protopirata, H. Trautschold, Zeitschr. deutsch. geol. Gesell.vol. xl. 

 1888, p. 753. 



Spine broad, laterally compressed, elongated and gently arched ; 

 convex margin armed with a series of large broad denticles, serrated, 

 and enveloped in ganoine : sides of the spine destitute of surface- 

 ornament and ganoine, being only marked by oblique transverse 

 sulci, each arising from the point of separation of two denticles, and 

 often implying the complete division of the spine into a series of 

 segments, easily detached one from another ; concave margin with- 

 out denticles. No distinct base of insertion. 



Originally regarded as portions of the jaw of a fish by J. Leidy l and 

 Newberry 2 , and compared with the rostral prolongation of Pristis by 

 L. Agassiz 3 , these remarkable fossils were first suspected to be Elas- 



1 Proc. Acad. Nat. Sci. Philad. vol. vii. (1856), p. 414. 



2 Pal. Illinois, vol. ii. (1866), p. 84. 



3 Proc. Amer. Assoc. Adv. Sci. 1855 (1856), p. 229. 



