﻿PAL^ONisnn/r,. 521 



chiostegal bones externally tuberculated or rugose. Fins large, 

 consisting of broad flattened rays, all articulated and distally bifur- 

 cating, more or less coated with ganoine ; anterior borders fringed 

 with well-developed fulcra. Dorsal and anal fins triangular in 

 shape, elevated, the dorsal opposed to the space between the pelvic 

 fins and the anal ; caudal fin bifurcated. Scales thick, of moderate 

 size, and highly ornamented ; not much deeper than broad upon the 

 middle of the flank, as deep as broad on the ventral aspect. Eacli 

 scale of the abdominal region marked in the hinder half by coarse 

 postero-inferiorly directed ridges and sharp denticulations, in its 

 anterior half by few, irregular, more or less interrupted vertical 

 ridges and furrows ; the scales of the caudal region coarsely serrated 

 posteriorly, with a few short transverse sculpturings anteriorly. 



The form of the upper lobe of the tail in this genus is as jet 

 unknown, but the characters of the head appear to justify its refer- 

 ence to the Palasoniscidse. In the original description of the fish, 

 the pelvic fin is referred to as anal, and the anterior margin of the 

 latter assigned to the caudal ; the supposed absence of an inner 

 keel upon the scales of the flank is also now proved to have been 

 assumed from imperfect evidence. 



Centrolepis aspera, Egerton. 



1844. Centrolepis aspei', L. Agassiz, Poiss. Foss. vol. ii. pt. i. p. 304 



(name only). 

 1858. Centrolepis asper, Sir P. Egerton, Figs. & Descrips. Brit. Organic 



Remains (Mem. Geol. Surv.), dec. ix. no. 5, pi. v. 

 1890. Centrolepis asper, A. S. Woodward, Ann. Mag. Nat. Hist. [6] 



vol. v. p. 430, pi. xvi. fig. 1. 



Type. Portion of head and trunk, with paired fins; British 

 Museum. 



The type species, attaining a length of about 0-25-0-3. Maxi- 

 mum depth of trunk equal to length of head with opercular appa- 

 ratus, and contained nearly four times in the total length ; snout 

 prominent and bluntly pointed; teeth long, slender, and acute, 

 sometimes gently curved; cranial roof ornamented with closely 

 arranged rounded tubercles, the posterior expansion of the maxilla 

 with similar tubercles and rugae, and the mandible with irregular 

 delicate striations, mostly directed longitudinally and sometimes 

 passing into small tubercles ; operculum, suboperculum, branchio- 

 stegal rays, and exposed portions of the pectoral arch also tuber- 

 culated, the clavicle sometimes in part rugose. Pelvic fins not 

 much inferior in size to the pectorals, arising behind the middle 



