ACAXTH0DIDJ3. 
13 
49668-9. One very stout specimen and an imperfectly preserved 
caudal region, with impression of the head and abdominal 
region; Thurso. Purchased , 1879. 
43967. Crushed fish, showing all the fin-spines ; Thurso. 
Purchased , 1872. 
38583. Slab with remains of several individuals. Purchased , 1864. 
Acanthodes mitchelli, Egerton. 
[Plate I. fig. 7.] 
1860. Acanthodes antiquus, Sir P. Egerton, Rep. Brit. Assoc. 1879, 
Trans. Sect. p. 116 (name only). 
1861. Acanthodes mitchelli , Sir P. Egerton, Rep. Brit. Assoc. 1860, 
Trans. Sect. p. 77; and Figs. & Descrips. Brit. Organic Remains 
(Mem. Geol. Surv.), dec. x. p. 61, pi. vii. 
1864. Acanthodes mitchelli . J. Powrie, Quart, Journ. Geol. Soc vol xx 
p. 419. 
1870. Acanthodes mitchelli, J. Powrie, Trans. Edinb. Geol. Soc. vol. i. 
p. 288, pi. x. fig. 1. 
1888. Mesacanthus mitchelli , R, H. Traquair, Geol. Mao- [3] yo l v 
p. 512. 
Type. Complete fish ; British Museum. 
A very small species, attaining a maximum length of 0-065. 
Body elongated and slender, the greatest depth being contained 
about six times in the total length ; cranial roof very coarsely 
rugose or consisting of large, irregular, tesserae-like membrane bones. 
Pelvic fins large, situated somewhat nearer to the anal than to the 
pectorals ; a pair of minute spines in advance of the pelvic pair. 
Pelvic spines about half as large as the pectorals, and two thirds as 
long as the anal. Dorsal fin arising behind the anal, larger than 
the latter. 
Form. Sf Loc. Lower Old Red Sandstone : Forfarshire. 
P. 560, P. 1330. iype specimen and a smaller more imperfect fish: 
Farnell, Forfarshire. The minute intermediate ventral 
spines are shown in Egerton’s outline sketch, but not in 
the detailed enlarged figure, and apparently not in the 
original specimen. The second fossil exhibits these 
spines. Egerton CoTl. 
35909. T wo contorted fishes ; Farnell. 
Presented by James Powrie, Esq., 1861. 
38594. Almost complete fish, lateral aspect, shown, of the natural 
size, in PI. I. fig. 7. 
Presented by James Powrie , Esq., 1864. 
