﻿152 ICHTHYODORULITES. 



mobranch spines by Leidy l and definitely recognized as such by 

 Sir Richard Owen 2 . They were also described as spines by New- 

 berry and Worthen a ; by Cope 4 and H. Woodward 5 the resemblance 

 between their segmented character and that of the Cretaceous Pele- 

 eopterus has been pointed out ; and Newberry 6 has recently 



Edestus minor, Newb. — Coal-Measures, Indiana, U.S.A. 



suggested that each spine may correspond to a series of spines such 

 as occurs upon the tail of some species of Trygon. Trautschold 7 has 

 revived the original hypothesis of Leidy ; and Miss Hitchcock 8 

 compares the fossil with the intermandibular arch of the Ganoid 

 Onychodus. 



Edestus heinrichsi, Newberry & Worthen. 

 1870. Edestus heinrichsii^ Newberry & Worthen, Pal. Illinois, vol. iv. 



p. 350, pi. i. fig. 1. 

 1879. Edestus heinrichii, J. S. Newberry, in Ann. Rep. Geol. Surv. 



Indiana, 1876-78, p. 347. 



Form. 8f hoc. Coal-Measures : Illinois and Indiana, U.S.A. 



1 Proc. Acad. Nat. Sci. Philad. vol. viii. (1857), p. 301. 



2 Palaeontology, ed. 2 (1861), p. 123. 



3 Pal. Illinois, vol. iv. (1870), p. 350. 



4 Vert.Cret. Form. West (Rep. U.S. Geol. Surv. Territ. vol. ii. 1875), p. 244 c. 



5 Geol. Mag. [3] vol. in. (1886), p. 6. 



6 Ann. New York Acad. Sci. vol. iv. (1888), p. 120. 



7 Bull. Soc. Imp. Nat. Moscou, 1883, pt. ii. p. 160. 

 » Amer. Nat, 1887, p. 847. 



