﻿536 ACTINOPTERTGTI. 



head continuing the downward slopo of the back in front of the 

 peak, with a slight convexity above and in advance of the orbit, 

 below which the facial profile is more abrupt; margins of maxilla, 

 premaxilla, and dentary toothless ; inner surface of maxilla and 

 pterygoid with cluster of small tubercular teeth ; oral aspect of 

 pterygoid and splenial bones with two sharp longitudinal ridges, 

 meeting posteriorly, and more or less coarsely denticulated. Pin- 

 rays closely articulated and distally bifurcating ; fulcra present on 

 all the fins. Pectoral fins small and delicate, laterally placed; 

 [pelvic fins unknown]. Dorsal and anal fins of nearly equal size 

 and shape, arising behind the dorsal and ventral peaks and termi- 

 nating at the base of the caudal pedicle, high and acuminate in 

 front, low and fringe-like in the posterior two-thirds ; caudal fin 

 deeply cleft, nearly equilobate. Scales ornamented with tubercu- 

 lations and striae, with smooth hinder border, and narrow over- 

 lapped anterior border ; principal flank-scales very deep and narrow, 

 with large anterior inner keel, and a large, broad, peg-and-socket 

 articulation extending nearly the entire width of the scale ; scales 

 dorsally and ventrally and towards the caudal pedicle less deep in 

 proportion to their breadth ; scales of upper caudal lobe relatively 

 small and lozenge-shaped. "Well-developed ridge-scales present 

 only upon the upper caudal lobe. 



The type species of this genus is known only by a detached 

 splenial bone, which is insufficient for precise diagnosis. It is de- 

 scribed as follows : — 



Clieirodus pes-rance, P. M'Coy, Ann. Mag. Nat. Hist. [2] vol. ii. 

 (1848), p, 131, and Brit. Pakeoz. Poss. (1855), p. 616, 

 pi. iii. a. fig. 9 ; E. H. Traquair, Ann. Mag. Nat. Hist. [5] 

 vol. ii. (1878), p. 17 ; J. W. Davis, Trans. Roy. Dublin Soc. 

 [2] vol. i. (1883), p. 523, pi. lxiii. fig. 5.— Upper Carboni- 

 ferous Limestone ; Derbyshire. [Woodwardian Museum, 

 Cambridge.] 



Cheirodus granulosus (Young). 



]866. Amphicentrum granulosum, J. Young, Quart. Journ. Geo! Soc. 



vol. xxii. p. 306, pi. xx. 

 1875. Amphicentrum granulosum, R. H. Traquair, Ann. Mag. Nat. 



Hist. [4] vol. xvi. p. 273, pi. ix. 

 1875. Amphicentrum granulosum, J. Ward, [Proc] N. Staffs. Nat. 



Field Club, p. 236. 

 1878. Clieirodus granulosus, R. H. Traquair, Ann. Mag. Nat. Hist. [5] 



vol. ii. p. 17. 



