PHOLIDOPHORUS. 101 



with rounded ridges as the bones of the cranial roof. They are deeply overlapping, 

 and their irregular ornamental ridges tend to be diagonal in direction. 



Remarks. — The fragmentary remains thus described are referred to Belonostomus 

 rather than to Aspidorhynchus, on account of the stout ossification of the vertebral 

 centra and the vertical grooving of the principal Hank-scales. They are distinguished 

 from the remains of all known species by the peculiar crenulation of the posterior 

 border of the principal flank-scales. The specific name now proposed for them is 

 given in honour of Mr. Reginald W. Hooley, F.GT.S., whose important discoveries 

 in the Wealden of the Isle of Wight are well known. 



Horizon and Localities. — Wealden : Isle of Wight, probably also Sevenoaks, 

 Kent (small scale in Sedgwick Museum, Cambridge, shown enlarged in PI. XXI, 

 fig. 3). 



Family Pholidoi'horid.e. 

 Genus PHOLIDOPHORUS, Agassiz. 



Pholidophorus, L. Agassiz, Neues Jahrb. fur Miu., etc., 1832, p. 145. 

 (?) Microns, L. Agassiz, Poiss. Foss., vol. ii, pt. i, 1833, p. 10. 



Generic Characters. — Trunk fusiform, not much deepened, and head relatively 

 large. External bones smooth or delicately ornamented with rugae and tubercu- 

 lations ; slime-canal on cheek-plates branched ; maxilla more or less arched, the 

 oral margin convex or nearly straight, with small conical or styliform teeth ; 

 mandibular teeth slightly larger, in single series. Lower expansion of pre- 

 operculum marked by radiating furrows ; suboperculum large, but smaller than 

 the trapezoidal operculum, from which it is divided by an oblique suture ; 

 interoperculum triangular and well forwards ; branchiostegal rays numerous. 

 Pleurocentra and hypocentra round notochord fused or separate. Fulcra present on 

 all the fins. Pectoral fins of moderate size, but larger than the pelvic pair; dorsal 

 and anal fins triangular, not extended, the former opposite to or arising somewhat 

 behind the pelvic fins ; caudal fin deeply forked. Squamation complete ; scales 

 thin and deeply overlapping, usually with an inner rib and peg-and-socket 

 articulation, and the external ganoine smooth or feebly ornamented ; principal flank- 

 scales deeper than broad, ventral scales in part broader than deep ; no enlarged 

 series of ridge-scales. Lateral line conspicuous. 



Type Species. — Pholidophorus bechei (L. Agassiz, Poiss. Foss., vol. ii, pt. i, 1844, 

 p. 272, pi. xxxix, figs. 1 — 4), from the Lower Lias of Lyme Regis, Dorset. 

 Additional details in Catal. Foss. Fishes, Brit. Mus., pt. hi (1895), p. 450, pi. xii, 

 figs. 1, 2. 



