152 
ICHTHYODORTJLITES. 
mobranch spines by Leidy 1 and definitely recognized as such by 
Sir Richard Owen 2 . They were also described as spines by New¬ 
berry and Worthen 3 ; by Cope 4 and H. Woodward 5 the resemblance 
between their segmented character and that of the Cretaceous Pele- 
copterus has been pointed out ; and Newberry 6 has recently 
Pig. 12. 
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 
Omjchodus. 
Edestus hemriciigi 9 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. Sf Log. Coal-Measures : Illinois and Indiana, TT.S.A. 
J' Tow OL , 
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. iii. (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. 
6 Amer. Nat. 1887, p. 847. 
