110 WEALDEN AND PURBECK FOSSIL FISHES. 



All the Bcales are smooth, with no posterior serrations. They are strengthened 

 on their inner face with a stout vertical ridge, and those of the abdominal region 

 are united by a large peg-and-socket articulation. They are arranged in nearly 

 10 regular transverse series; and above the origin of the pelvic fin the series 

 comprises 1 1 or 12 scales, of which the lateral line traverses the seventh or eighth 

 from the ventral border. In the abdominal region (PI. XXII, fig. la), the scales of 

 the lateral line are from four to three times as deep as broad; the next scales 

 above and below these 1 are about twice as deep as broad; the next above and 

 below are still somewhat, deeper than broad; those dorsally and ventrally are 

 smaller and nearly equilateral, or even broader than deep. The very narrow 

 flattened ventral face of the abdominal region is covered with small rhombic 

 seales; and there seem to have been slightly enlarged and modified scales, with 

 two or three posterior denticulations, round the anus. In the caudal region 

 ( PI. XXII, fig. \h) the scales of the lateral line still remain somewhat deeper than 

 broad, and they are crossed very obliquely by the slime-canal. The other caudal 

 scales are rhombic and nearly equilateral, with a tendency to the rounding of the 

 hinder and upper margins. There is no conspicuously enlarged ridge-scale on 

 the caudal pedicle above or below, but there seem to be two or three short and 

 broad dorsal ridge-scales. The lateral line is marked only by a faint smooth ridge. 



Horizons and Localities. — Lower Purbeck Beds: Portland, Dorset; Teffont, 

 Wiltshire. .Middle Purbeck Beds : Swanaere, Dorset. 



"O^j 



4. Pholidophorus brevis, Davies. Plate XXII, figs. 4, 5. 



L887. Pholidophorus brevis, W. Davies, Geol. Mag. [3], vol. iv, p. o38, pi. x, fig. 1. 



Type. — Imperfect fish ; British Museum. 



Specific Characters. — A stout mutation of P. purbeclcensis, with a comparatively 

 short and robust caudal region. 



Description of Specimens.— The type specimen (PL XXII, fig. 4), from the 

 Upper Purbeck Beds, is distorted, so that the head is accidentally shortened and 

 the abdominal region deepened, but it evidently represents a shorter and stouter 

 fish than the Lower Purbeckian J', purbeclcensis. Part of a second specimen, in 

 counterpart in the Egerton and Enniskillen Collections, indicates an equally stout 

 form (PI. XXII, fig. 5). 



In the latter fossil the head appears to exhibit its true shape; and its length 

 to the back of the opercular apparatus clearly equals the maximum depth of the 



lk - Traces of a coarse rugosity are seen on the cranial roof. Stout conical 



th. some with a slightly curved apex, occur in both jaws of the type specimen. 

 - less than half as deep as the operculum in both specimens, 

 e remains of the very delicate ring- vertebras are preserved especially 

 m the counterpart of the specimen figured in PL XXII, fig. 5. 



