PLETJROPHOLIS. 119 



The second specimen (fig. 13), of which the jaws, shown mainly in impression, 

 are somewhat displaced forwards, exhibits also traces of an ossified sclerotic. 



Only fragments of the fins are preserved, but the places of origin of allexcept 

 the dorsal are seen in the second specimen, where the extent of the forked caudal 

 is also traceable. Stout deeply overlapping fulcra fringe the pelvic, anal, and 

 caudal fins, those at the origin of the lower lobe of the caudal fin in the type 

 specimen being displaced and especially conspicuous. The distantly articulated 

 rays in the lower caudal lobe are especially well enamelled. 



The scales must have been in about 40 transverse series. Some of the 

 deepened flank-scales in the type specimen exhibit an irregular waviness of the 

 outer face, doubtless following lines of growth, while those of the second specimen 

 are exposed from within, showing the broad vertical ridge on their inner face, and 

 the peg-and-socket articulation. The caudal scales preserved in the type specimen 

 are clearly not serrated, while those in the second specimen, though bearing the 

 internal ridge, lack the peg-and-socket articulation. As shown in PL - XXIII, 

 fig. 13, the lateral line curves down the second deepened flank-scale to traverse 

 the usual ventral row of nearly equilateral scales ; as shown on the tail of the type 

 specimen, its course is marked by a slight smooth ridge on the outer face. 



Horizon and Locality. — Middle Purbeck Beds: Durdlestone Bay, Swanage, 

 Dorset. 



k Pleuropholis longicauda, Egerton. Plate XXIV, figs. 1,2; Text-figure 35b. 



lfi-58. Plewropliolh longicaudus, P. M. Gr. Egerton, Figs, and Descripts. Brit. Organic Remains (Mem. 



Geol. Snrv.), dec. ix, no. 7, p. 3, pi. vii, fig. 4. 

 1895. Pleuropholis longicaudata, A. S. Woodward, Catal. Poss. Fishes, Brit. Mus., pt. iii, p. 483. 



Type. — Imperfect fish ; apparently lost. 



Specific Characters. — Imperfectly known, but attaining a length of about 9 cm., 

 and the head with opercitlar apparatus occupying somewhat more than one-sixth of 

 this length. Probably distinguished from all other known species by the depres- 

 sion of the head, which seems to have been scarcely more than half as deep as the 

 middle part of the trunk. Scales smooth, not serrated ; the rhombic dorsal and 

 ventral scales often produced to a sharp point at their postero-inferior angle. 



Description, of Specimens. — The type specimen (Text-fig. 35b, p. 114), which 

 was in Mr. W. R. Brodie's Collection, cannot now be traced, and the description and 

 figure given by Egerton are insufficient to diagnose the species. One specimen in 

 the British Museum, however, from the Middle Purbeck Beds of Swanage, is 

 labelled " Pleuropholis longicaudus " by Egerton, and two other specimens from 

 the same formation and locality also seem to belong to this species. It may, 

 therefore, probably be defined as above. 



The head seems to be crushed upwards in the type specimen. Its compara- 



