﻿300 arthrodira. 



I>y E. von Eichwald (torn. cit. p. 1529, pi. lvii. figs. 4, 5), the 

 originals of Pander's pi. vii. figs. 3, 9, 15, are assigned to C. ver- 

 neuili ; while those of the latter author's pi. vii. figs. 3 6, &', 11, 12, 

 14, with an indeterminable fragment named " plaque dentaire," are 

 regarded as the types of a distinct species, C.posthumus. The so- 

 called C. grifflthii, M'Coy (Ann. Mag. 2s 1 at. Hist. [2] vol. ii. 1848, 

 p. 8), from the Lower Carboniferous of Cultra, Co. Down, Ireland, 

 is a generically indeterminable jaw (C. H. Pander, op. cit. p. 87). 

 [Dublin Museum.] 



Genus DINICHTHYS, dewberry. 



[Eep. Geol. Surv. Ohio, vol. i. pt. ii. 1873, p. 313.] 



Head and trunk broad, the dorsal aspect slightly arched from side 

 to side ; scutes smooth or feebly marked with vermiculating rugae ; 

 caudal region destitute of armour. Elements of cranial shield almost 

 or completely fused in the adult, and the occipital bones constituting 

 less than half of its total length ; a distinct small median hone over 

 the pineal region, with a minute perforation ; orbits forming broad 

 notches, not bounded externally : eye with a ring of few sclerotic 

 plates ; maxilla distinct, and two inner pairs of dentigerous bones in 

 the upper jaw ; mandibular rami suturally united at the symphysis, 

 each beak-shaped in front, and bearing a short, single series of 



A. 



Diagrams of dentition of Dinichthys, after Newberry. — A, anterior, and B, 

 lateral aspect of jaws of D. terrelli ; C, anterior aspect of jaws of 

 D. hertzeri. 



acute teeth anchylosed just in advance of the middle of its oral 

 margin. A single median dorsal shield upon the trunk, with an 

 inner longitudinal keel, and rounded or acutely pointed posteriorly ; 

 ventral armour of trunk well developed, consisting of two large 

 lateral plates and a long narrow median element equivalent to the 

 two diamond-shaped median bones of Coccosteus fused together ; 

 ventral and dorsal armour united by lateral plates, of which the 

 anterior dorso-lateral exhibits a large articulating eminence, but has 



