﻿C0CC0STEID.B, 299 



Fragments of the shield of an undetermined species of Pldyclam- 

 aspis, with an ornamentation much resembling that of P. anglica, 

 have also been discovered in the Lower Devonian of Kussian Poland 

 (Coccosteus, A. von Alth, Abhandl. k. k. geol. Eeichsanst. vol. vii. 

 pt. i. 1874, p. 38, pi. iii. figs. 16-21). 



Genus CHELYOPHORUS, Agassiz. 



[Poiss. Foss. V. G. R. 1845, p. 135.] 



Dorsal shield arched from side to side ; scutes ornamented with 

 granulations, more or less elongated, confluent, and often arranged 

 in sinuous or vermiculating lines ; neural and haemal arches well 

 calcified, and the caudal region destitute of armour. Elements of 

 cranial shield not fused in the adult, and the occipital bones consti- 

 tuting less than half of its length ; orbits forming broad notches, 

 not bounded externally ; a median pineal foramen ; parachordal 

 cartilage ossified ; [jaws unknown]. Dermal armour of trunk pro- 

 bably as in Coccosteus. 



This genus comprises species of small or moderate size, and does 

 not appear to be represented in the Collection. The finest specimen 

 hitherto described is the imperfect head and trunk of C. primigenius 

 in the University of St. Petersburg ; this showing one of the support- 

 ing cartilages of the dorsal fin, interpreted by Eichwald as a dorsal 

 fin-spine. There is no certain evidence of paired appendages. 

 Several detached plates have been described and figured by Pander 

 (Placoderm. devon. Syst. p. 86, pi. vii. figs. 3, 9-15, 31), and com- 

 pared with the corresponding plates of other genera ; and the follow- 

 ing species are recognized : — 



Chelyophorus primigenius, E. von Eichwald, Leth. Rossiea, vol. i. 

 (1860), p. 1525, pi. lvii. figs. 1-3.— Devonian ; Govt, of 

 Orel. [Imperfect skeleton ; University of St. Peters- 

 burg.] 



Chelyophorus verneuili, L. Agassiz, Poiss. Foss. Y. G. R. (1845), 

 p. 135, pi. xxxi. a. figs. 14-19 j G. Fischer de Waldheim, 

 Bull. Soc. Imp. Nat. Moscou, vol. xxv. (1852), pt. i. p. 172, 

 pi. ii. figs. 1-5 ; E. von Eichwald, Leth. Rossica, vol. i. 

 (1860), p. 1529 ; C. H. Pander, Placoderm. devon. Syst. 

 (1857), p. 96 ; H. Trautschold, Zeitschr. deutsch. geol. 

 Ges. vol. xli. (1889), p. 46, pi. vi. figs. 3-6. — Devonian ; 

 Govt, of Orel and Livonia. [The type species, founded on 

 detached plates.] 



