12 
ACANTHODII. 
35786. A comparatively large specimen, shown, of the natural size, 
in PI. I. fig. 5 ; Tynet Burn. The fish is distorted, and 
the outlines are somewhat obscured by the displacement 
of the scales ; but several details are exhibited. In the 
head, the cartilages of the upper and lower jaws are indi¬ 
cated, and the ring of circumorbital dermal plates is 
preserved. Only a portion of one pectoral spine is observ¬ 
able ; but the pelvic fin of the left side, with its spine, is 
complete, and exhibits a verj’ long base-line. The large 
anal spine also occurs in position in front of a much elon¬ 
gated fin ; and there is a fragment of the dorsal spine in 
its ordinary position. The upper caudal lobe is somewhat 
broken towards the extremity, but otherwise well pre¬ 
served, as is also the greater portion of the caudal fin. 
Purchased , 1860. 
43019. A small coiled-up specimen, preserved in counterpart ; 
Tynet Burn. Purchased, , 1871. 
P. 1329. Four small specimens, two being associated in one nodule. 
The largest of the latter is shown, of the natural size, in 
PI. I. fig. 6 ; Tynet Burn. Egerton Coll. 
Acanthodes peachi, Egerton. 
1861. Acanthodes peachi, Sir P. Egerton, Figs. & Descrips. Brit. Organic 
Remains (Mem. Geol. Surv.), dec. x. p. 57, pi. vi. figs. 1, 2. 
1861. Acanthodes conaceus, Sir P. Egerton, ibid. p. 59, pi. vi. figs. 3-5. 
[Museum of Practical Geology.] 
1888. Mesacanthus peackii , R. II. Traquair, Geol. Mag. [3] vol. v. p. 512. 
Type. Nearly complete fish; Museum of Practical Geology, 
London. 
A very small species, attaining a maximum length of about 0*06. 
Body more robust than in A. pusillus , the greatest depth being con¬ 
tained about five or six times in the total length. Pelvic fins large, 
midway between the pectorals and the anal ; pelvic spines smaller 
than the pectorals, but almost or quite as long as the anal spine. 
Dorsal fin arising slightly behind the anal, and much larger than 
the latter. 
Form. Sf Loc. Lower Old Red Sandstone : Caithness, Scotland. 
33148. Imperfect specimen, showing the dorsal, anal, and pelvic 
spines, with portions of the pectorals and pectoral basi- 
pterygium ; Thurso. Purchased. 
