A. 8. Woodward — Canadian Devonian Fishes. 483 



quarters the natural size in PI. XIII. Fi^. 1. The head and 

 extremity of the tail are imperfect in both specimens, and the 

 pectoral fins are only fragmentary ; but otherwise the general form 

 and proportions of the fish are well shown. 



In the head the large dermal tesserae on the cranial roof, and 

 part of the narrow ring round the orbit {orb.), are exhibited by both 

 specimens; and there is a pair of small elements postero-inferiorly 

 (s.), each with a triangular expansion at one end, a contraction 

 mesially, and a less expansion at the other end, probably repre- 

 senting the " styliform bone." Behind the orbit in the type 

 specimen, there is also evidence of a vertically-elongated, super- 

 ficially-calcified cartilage, apparently the hyomandibular. The as- 

 cending portion of the scapular arch (x.) is distinct behind the head ; 

 and in the type-specimen one of the median spines (m.) is well 

 shown immediately within the base of the pectoral fin-spine [pet). 

 The intermediate ventral spines («.) are well developed and exhibited 

 in both specimens; and the very large pelvic fin-spines {ph.) also 

 occur in both. All the median fin-spines are more or less fractured, 

 though their proportions are satisfactorily indicated {d^. d^- a.) ; and 

 in the type specimen the fin-membrane is seen to extend to the 

 extremity of the spine in the two dorsals. All the fin-spines exhibit 

 a single deep groove close to and parallel with their anterior 

 border ; and the lateral face behind this groove is feebly marked 

 with longitudinal striations, especially in the anal fin of the second 

 specimen. The caudal fin (c.) shows the ordinary Acanthodian 

 characters, and there are traces of the robust, calcified heemal arches 

 of the axial skeleton at the base of its lower lobe. The scales 

 (Fig. la) are very conspicuously ornamented, and the slight enlarge- 

 ment of the two rows of scales bordering the lateral line in the 

 abdominal region is distinct in both specimens. 



Affinities. — The species thus indicated belongs to the genus Dipla- 

 cantkus, as defined in the British Museum Catalogue (Pt. II. p. 23), 

 and differs notably from the most closely allied species, D. longispirnis, 

 in the very large size of the median fin-spines, and in their relative 

 dimensions as noted in the diagnosis. 



Coccosteus canadensis, sp. nov. [Plate XIII. Fig. 2.] 



This species as yet is not satisfactorily definable, being known 

 only by a weathered beach-pebble exhibiting an impression of the 

 head-shield. The features shown, however, suflSce to readily dis- 

 tinguish this shield from all described forms except the typical 

 Coccosteus decipiens ; and from the head-shield of the latter it 

 evidently differs (i) in its greater length as compared with the 

 breadth, (ii) in the narrower median occipital, and (iii) in the rela- 

 tively smaller size of the central plates. 



Almost the whole of the border of the shield is destroyed, but 

 most of the sutures and the sensory canals are distinctly exhibited 

 in impression. The median occipital plate (m. occ.) is considerably 

 more than twice as broad behind as in front, and its superficial 

 tuberculations are arranged in radiating series towards the posterior 



