RBTZODOXTIDJE. 
361 
1875. Tristichopterus alatus, R. H. Traquair, Proc. Roy. Soc. Edinb. 
vol. viii. p. 513. 
1875. Tristichopterus cdatus , R. H. Traquair, Trans. Roy. Soc. Edinb. 
vol. xxvii. p. 383, pi. xxxii. 
Type. Imperfect fishes ; Museum of Practical Geology and British 
Museum. 
The type species, attaining a length of about 0'3. Maximum 
depth of trunk nearly equal to the length of the head, and contained 
about six and a half times in the total length. Head somewhat 
longer than deep : operculum deeper than broad; all the bones 
ornamented with granulations, more or less fused into short tor¬ 
tuous rugae. Pelvic fins about three quarters the size of the pec¬ 
torals, arising immediately behind the middle point of the trunk, 
and opposed to the somewhat smaller anterior dorsal fin ; posterior 
dorsal and anal fins of nearly equal size, deeper than broad, and 
much larger than the anterior dorsal; length of caudal fin much 
less than its maximum depth. Scale-ornament very fine and closely 
arranged. 
Form. Sf Loc. Lower Old Red Sandstone: Caithness. . 
All the specimens mentioned below are comprised in the Peach 
Collection, and were obtained from the neighbourhood of John 
o’Groats. 
42396. Counterpart of one of the type specimens figured by Egerton, 
loc. cit. pi. v. 
42397. Eish, showing well-preserved caudal region, noticed by 
Traquair, loc. cit. 1875, p. 384. 
42398. Imperfect head and anterior part of abdominal region, with 
right pectoral fin. The tubercular and partly rugose 
ornamentation of the head-bones is distinct, and portions 
of the broad, ring-shaped vertebras occur. 
42406. Imperfect trunk with part of the head and large portions 
of the fins. 
42407. Part of the squamation of a large fish, with remains of the 
axial endoskeleton and some of the fin-supports. 
Genus EUSTHENOPTERON, Whiteaves. 
[Canadian Naturalist, n. s. vol. x. 1881, p. 30.] 
Body much depressed anteriorly, with round or ovoid scales, of 
which the exposed portion is ornamented with granulations and 
antero-posteriorly directed rugae. Head-bones more or less tuber- 
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