HOPLOPTERYX. 23 



3. Hoplopteryx simus, sp. nov. Plate VIII, figs. 1 — 4 ; Text-figure 5 c. 



1837-39. Beryx oniatus, L. Agassiz (errore), Poiss. Foss., vol. iv, p. 117, pi. xiv d, fig. 2. 



Ti/pe. — Imperfect head ; British Museum. 



Specific Character!^. — An imperfectly known species, probably not exceeding 

 20 cm. in length. Length of head with opercular apparatus considerably less than 

 the maximum depth of the trunk. Tubercular and rugose ornament of external 

 bones very coarse, the rounded tubercles being especially large on the shortened 

 snout. Operculum twice as deep as broad. Scales moderately thick, with short 

 but coarse pectinations at the hinder border ; all the scales smaller than usual in 

 the genus, probably almost 20 in a transverse series on the trunk ; the lateral line 

 traversing about the fourteenth longitudinal series above the ventral border. 



Description, of Speciineiis. — The type specimen (B. M. no. 49073) displays 

 remains of a head of the typical Hoplopteri/x-type, with unusually coarse and 

 strongly-developed ornament, which is very conspicuous on the shortened snout, 

 and is so much developed on the lower part of the mandible as to form bridges 

 over its slime-canal and thus partially sul)divide it (PI. VIII, fig. 3). A similar head 

 in association with remains of the greater part of the trunk (B. M. no. P. 387) 

 shows that the fish must have had much the same proportions as H. leicesiensis, 

 with an inferiorly-flattened abdominal region. 



Other imperfect examples of the head in the British Museum display nearly all 

 its principal characters, and show the curiously shortened form of the cranium 

 (Text-fig. 5 c). A fracture in B. M. no. P. 5700 reveals evidence of a basicranial 

 canal. The smooth floor of the extensive depression of which the supraoccipital 

 forms a large part, is exhibited in one specimen (PI. VIII, fig. 1, socc.) ; and its 

 lateral bounding wall, ornamented externally at the upper edge by large rounded 

 tubercles, is shown in other specimens (e. g., PI. VIII, fig. 2, /■.). In advance of the 

 anterior apex of this cavity the frontals (fig. 1,,/V.) are thickened by a mass of 

 large, smooth tubercles, Avliich cluster round a pair of anterior frontal slime-pits (ii) 

 and spread outwards into a similar tuberculation and thickening of the supraorbital 

 flange. The mesethmoid {eth.), which is about twice as broad as long, completes 

 the cranium in front, with a re-entering angle for the ascending processes of the 

 premaxillffi. Its anterior and lateral borders are also much thickened by a cluster 

 of large rounded tuljercles, which Ijound another pair of slime-pits (in). These 

 are somewhat larger than the anterior frontal pits, and each is directly connected 

 with the latter of the same side by a foramen through the intervening barrier, 

 which evidently corresponds Avith the thin spicular In-idge of l)one occupying the 

 same position in //. lewesieiisis. 



The mouth is as large as in IL leicesiensis, but tliere are differences in the shape 



