482 A. 8. Woodward — Canadian Devonian Fishes. ' 



Acanthaspis ;^ and so far as can be judged from known specimens, 

 they only differ from the hist- mentioned spines in the circumstance, 

 that the supporting plate is destitute of the extended oblique pedicle 

 observed both in the type specimens from the Corniferous Lime- 

 stone of Ohio and in the shield assigned to the same genus from 

 Spitzbergen.^ It thus remains to discover more associated examples 

 of the plates and spines from Ohio, to determine whether they 

 actually pertain to Ostracoderms, as suspected, or whether they 

 represent part of the armour characteristic of Arthrodira ; for the 

 fixed spinous appendage is now proved to occur in both of these 

 widely sej)arated groups. 



Fig. 1. — Spinous appendage of dermal armour of Phhjctwnaspis acadica, 



II. New Species from the Upper Devonian, Scaumenac Bat. 



The fossils from Scaumenac Bay comprise numei'ous fine examples 

 of the known species of Bothriolepis, Acanthodes, Phaneropleuron, 

 Enslheitopteron, and CheiroJppis. Among them there are also remains 

 of two additional genera, hitherto not discovered in Canada ; and the 

 best of these specimens are shown in Plate XIII. One genus is the 

 Acanthodian Diplacanthus, only known previously from the Lower 

 Old Ked Sandstone of Scotland ; the other is Coccosteus, of very 

 wide range in the Old Ked Sandstone, both as regards time and space, 



Diplacanthus liorridns, sp. nov. [Plate XIII. Fig. 1.] 



Sp. Char. — A species of moderate size, attaining a length of not 

 less than 0*12; the greatest depth of the trunk contained about 

 four times in the total length of the fish. Fin-spines much elongated, 

 with one deep longitudinal sulcus parallel to the anterior margin, 

 and the sides either smooth or very finely striated. [Pectoral fin- 

 spines incompletely known] : median pectorals conspicuous, close 

 to the former; pelvic fin-spines relatively large, about equalling 

 the anal fin-spine in size. Dorsal fin-spines very large and elongated, 

 the length of the first much exceeding the depth of the trunk at its 

 point of insertion, equalling the length of the space between the 

 two dorsal fin-spines, and larger than the second fin-spine, which is 

 directly opposecf to the anal fin-spine, and equals the latter in size. 

 Scales marked with prominent radiating furrows and ridges ; those 

 of the lateral line in the abdominal region slightly enlarged. 



Specimens. — This species is determined on the evidence of two 

 specimens, of which the type, in counterpart, is shown of three- 



1 J. S. Newberry, "Fishes of the Devonian System," Geol. Surv. Ohio, vol. ii. 

 pt. ii. p. 36 (1875). 



- Smith \Voodward, "The Devonian Fish-Fauua of Spitzbergen," Ann. Mag. 

 Nat. Hist. [6] vol. viii. p. 4, pi. i. (1891). 



