EV PERMIAN FOSSILS. 
dorsal fin. This remarkable discrepancy in form and proportion is associated 
with other peculiarities in the outline, number, and character of the scales. 
As in other species of the genus, these are small and uniform, but they are more 
numerous, there being not less than sixty in each dorso-ventral series in the broad 
part of the body. The arrangement of each series is less oblique; and the scales are 
less elongated, especially near the tail, than in Pygoplerus mandibularis. ‘The scales are 
ornamented with four or five distinct ridges, somewhat in the manner of those of 
Acrolepis. ‘These are not so numerous, nor so prominent in the caudal region. The 
bones supporting the dorsal fin rays are strong and much compressed: those of the 
anal fin are larger and more numerous, but not flattened. It is a very distinct and 
well characterised species.—P. G. E. 
Sir Philip Egerton’s specimen of this species was found in the Marl-Slate of | 
Ferry-Hill. 
Genus Acrolepis, Agassiz. 
ACROLEPIS SEDGWICKII, Agassiz. Plate XXV, fig. 1 a, 4, ¢. 
FRAGMENT OF A FOSSIL FISH; SPECIES NOT ASCERTAINED, Sedgwick. Traus. Geol. Soc. 
Lond., 2d series, vol. iii, p. 117, pl. vii, figs. 3, 4, 1829. 
ACROLEPIS SEDGWICKII, Agassiz. Poiss. Foss., vol. i, part i, pp. 80, 81, pl. In. 
Broun, Letheea Geognostica, vol. ii, p. 128, pl. x, 
fig. 6, 1835. 
= — Hs Ann. Mag. Nat. Hist., vol. vii, p. 488, 1841. 
Morris, Catalogue, p. 187, 1843. 
— Rep. 13th Meet. Brit. Assoc., p. 198, 1844. 
— = a De Verneuil, Bull. Soc. Géol. de France, 2™° série, 
vol. i, p. 40, 1844. 
== — BA Geol. Russ., vol. i, p. 227, 1845. 
- _ Tennant, Strat. List, p. 89, 1847. 
— — 55 King, Catalogue, p. 15, 1848. 
= — ae Howse, Trans. T. N. F. C., vol.1, p. 236, 1848. 
a2 
The specimen selected to give the best idea of this interesting species is from my 
own collection. Although it is rather more perfect than Mr. Witham’s specimen 
fizured in the ‘ Poissons Fossiles;’ yet it is deficient in those parts still wanting to 
complete the description of the species, viz. the head, and scapular arch and appen- 
dages. The account given by Agassiz is so full and accurate, that it is unnecessary to 
repeat it here, especially as the subject of the plate was examined by Agassiz before 
his detailed description was printed. Since the publication of the ‘ Poissons Fossiles,’ 
a species of this genus has been discovered in the Coal-shale of Berschweiler near 
Kirn, on the Nahe, so that every genus of Permian fish is now known to be common 
to that system and the Coal-measures.—P. G. E. 
Acrolepis Sedywickit occurs in Mar]-slate at Kast Thickley, Ferry-Hill, Thrislington 
Gap, and Whitley. 
