HOPLOPTERVX. 15 



1850. Berijx oniafiis, F. Dixou, Geol. Sussex, p. 371, pi. xxxiv, fig. 1, pi. xxxvi, figs. 1, 3. 

 1888. IIo]_)lo]}terya' leivesiensis, A. S. Woodward, Proc. Geol. Assoc, vol. x, p. 327. 

 1901. HopJopterijx lewesiensis, A. S. Woodward, Catiil. Foss. Fishes B. M., pt. iv, p. 397, pi. xvi, 

 fig. 4, text-fig. 13. 



Ti/pe. — Imperfect fisli, pi'ol)a])ly from one of the Turonian zones ; Briti.-^h 

 Museum. 



Specific Gharncters. — A species attaining a length of about 30 cm. Length of 

 head with opercular apparatus considerably less than the maximum depth of the 

 trunk, "which nearly equals the length from the hinder margin of the clavicle to 

 the base of the caudal fin. Tubercular and rugose ornament of external bones 

 rather fine. Operculum twice as deep as broad. Dorsal fin occupying nearly one 

 half of the back, comprising G very stout, longitudinally ril)bed spines and 8 to 10 



Fig. 4. Hoplopteryx lewesiensis, Mantell; restoration, about one half nat. size. — English Chalk. 



divided rays, the length of the longest spine almost equalling one third the deptli 

 of the trunk at its insertion ; anal fin with 7 or 8 divided rays preceded by 3 or 4- 

 very stout spines, which gradually increase to a length about equalling that of the 

 longest dorsal. Scales very finely rugose and delicately pectinated ; the lateral 

 line traversing about the ninth longitudinal series above the ventral border. 



Description of Sjiecimena. — The type specimen in the Mantell Collection (nos. 

 4014-15) is too imperfect to exhibit many of its generic and specific characters; 

 but, on direct comparison, it is clearly proved to be specifically identical with 

 certain better-preserved fossils on which the foregoing diagnosis is based. Part 

 of the left side of the head and opercular apparatus is exposed from within, and 

 the operculum shows its two characteristic spines. The imperfect trunk is a little 

 distorted and shows only fragments of the vertelu'al column and median fins, with 



