﻿1 20 I0HTHYODOKULITE8. 



P. 6254. Two specimens ; Allemagne. EnnisMJen Coll. 



A fragment of an Asterolepid appendage from the Devonian of 

 Russia has been erroneously assigned to this genus under the name 

 of Pristctcanthus marinus, E. von Eichwald (Bull. Soc. Imp. Nat. 

 Moscou, vol. xvii. 1844, p. 826 (marianus), and ibid. vol. xix. 1846, 

 pt. ii. p. 294, pi. x. figs. 10, 11, and Leth. Eossica, vol. i. 1860, 

 p. 1605). 



Genus CCELORHYNCHUS, Agassiz. 

 [Poiss. Foss. vol. v. pt. i. 1844, p. 92.] 



Syn. Cylindracanthus, J. Leidy, Proc. Acad. Nat. Sci. Philad. 1856, 

 p. 12. 



Spine very long, slender, and gradually tapering, rounded in sec- 

 tion, and without denticles ; external surface longitudinally ridged 

 and grooved, each ridge corresponding to a wedge-shaped plate, 

 which forms a small sector of the spine. Central cavity -relatively 

 small, sometimes in part simple, but usually divided by a median 

 partition; a division plane passing through the middle of the 

 partition, thus allowing the spine to be readily split into two sym- 

 metrical halves. 



This ichthyodorulite was originally mistaken by Agassiz for the 

 rostrum of a Xiphioid Teleostean, and its truly dermal nature was 

 first demonstrated by W. C. Williamson \ A Cretaceous example 

 in the Willett Collection, Brighton Museum, suggests that the fossil 

 may be referable to an undetermined Chimasroid 2 . 



Ccelorhynchus rectus, Agassiz. 



1784. " Petrification inconnue," Burtin, Oryctogr. Bruxelles, pi. vi. 



figs. A-E. 

 1844. Ccelorhynchus rectus, L. Agassiz, Poiss. Foss. vol. v. pt. i. p. 92 



(name only). 

 1850. Ccelorhynchus, F. Dixon, Foss. Sussex, p. 112, pi. x. figs. 14-17, 



pi. xi. fig. 26. 

 1861. Ccelorhynchus rectus, R. Owen, Palaeontology, ed. 2, p. 172, 



woodc. fig. 80. 

 1871. Ccelorhynchus burtini and C. rectus, H. Le Hon, Prelim. Mem. 



Poiss. Tert. Belg. p. 14. 

 1871. Ccelorhynchus burtinii and C. rectus, P. J. Van Beneden, Bull. 



Acad. Roy. Belg. [2] vol. xxxi. p. 500. 



1 Pbil. Trans. 1849, p. 471, pi. xliii. figs. 35-37, and ibid. 1851, p. 667. 



2 A. S. Woodward, Ann. Mag. Nat. Hist. [6] vol. ii. (1888), p. 223. 





