﻿paljsoniscid^:. 503 



abdominal region are nearly parallel, while those on the caudal 

 region gradually converge towards the postero-inferior angle of the 

 scale, and thus exhibit a branched arrangement. 



The supposed differences in the scale-ornament and the sculpture 

 of the ganoine on the caudal fin-rays noted by Agassiz in A. sedg- 

 ivicki and the so-called A. asper, appear from later discoveries to be 

 entirely due to differences in the state of preservation. 



Form. <$f Loc. Upper Permian (Marl Slate) : Durham. Upper 

 Permian (Kupferschiefer) : Germany. 



(i.) Marl Slate. 



P. 3407. Pish 0*65 in length, lateral aspect, exhibiting large 

 portions of all the fins except the dorsal; Midderidge. 

 The form of the maxilla is distinct, and the ornamenta- 

 tion of most of the head and opercular bones is displayed. 

 Much of the sqnamation is preserved, but the majority 

 of the scales are seen from the inner aspect, while others 

 are indicated as mere impressions of the external orna- 

 mented surface. Enniskillen Coll, 



P. 553. Posterior half of abdominal region and the tail, with fins, 

 noticed and figured by Egerton, loc. cit. 1850 ; Ferry Hill. 



Egerton Coll. 



P. 3406. Imperfect caudal region, wanting the anal fin and the 

 greater portion of the dorsal, associated with some scat- 

 tered head-bones ; Perry Hill. One of the small pelvic 

 fins is also observed anteriorly. Enniskillen Coll. 



(ii.) Kupferschiefer. 



P. 3411. Type specimen of Acrolepis asjper described by Agassiz, 

 agreeing in size and proportions with no. P. 3407 ; Mans- 

 feld, Thuringia. Many parts of the fossil are somewhat 

 obscured by a thin film of matrix. The suboperculum 

 and branchiostegal rays are well shown ; and of the fins 

 only the distal portions of the anal and caudal are broken 

 away. The ganoine-coated articulations of the fin-rays 

 were mistaken by Agassiz, as in some other Palaeoniscida?, 

 for an investment of ganoid scales. Enniskillen Coll. 



15401. Imperfect head, opercular apparatus, and anterior scales ; 

 Thuringia. Purchased, 1840. 



