PALiEONISCIDJE. 
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- 
wicki and the so-called A. asper , appear from later discoveries to be 
entirely due to differences in the state of preservation. 
Form, df Log. 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 squamation 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, loo. cit. 1850 ; Perry 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 asper 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 Palseoniscidse, 
for an investment of ganoid scales. Enniskillen Coll. 
15401. Imperfect head, opercular apparatus, and anterior scales ; 
Thuringia. Purchased , 1840. 
