ICHTHYODORT7LITE3. 
155 
Genus EUCTENIUS, Traquair. 
[Geol. Mag. [2] vol. viii. 188], pp. 36, 334.] 
Small dermal defence somewhat elliptical in shape, laterally com¬ 
pressed, convex on one side, concave on the other, with one margin 
nearly straight, the opposite margin evenly convex, one extremity 
rounded or bluntly pointed, and the other tapering to a point or 
produced into a long narrow extension. Convex margin divided 
in a comb-like manner into a series of closely arranged, acutely 
pointed denticles. 
Fossils of this character have been assigned by Anton Fritschto 
the cloacal region of certain Permian Amphibia under the name of 
“ Kammplatten.” 1 
Euctenius unilateralis (W. J. Barkas). 
1869. Ctenoptychius, T. P. Barkas, Geol. Mag. vol. vi. p. 43, woodc. figs. 
1 , 2 . 
1873. Ctenoptychius, T. P. Barkas, Coal Meas. Palseont. p. 18, figs. 
22, 23. 
1874. Ctenoptychius unilateralis, W. J. Barkas, Monthly Rev. Dental 
Surgery, vol. ii. p. 484, figs, xvi, xvii. 
1875. Ctenoptychius unilateralis, J. Ward, [Proc.] N. Staffs. Nat. Field 
Club, p. 220. 
1881. “ Ctenoptychius ” unilateralis, R. H. Traquair, Geol. Mag. [2] 
vol. viii. p. 335. 
1890. JEuctenius unilateralis, J. Ward, Trans. N. Staffs. Inst. Mining 
Engineers, vol. x. p. 152, pi. ii. fig. 14. 
Type. Collection of T. P. Barkas, Esq., Newcastle-upon-Tyne. 
The type species. 
JEuctenius unilateralis (Barkas).—Coal-Measures, Newcastle-upon-Tyne. 
The upper figure is twice, and the lower figure thrice the natural size. 
Form. Loc. Coal-Measures : Staffordshire, Northumberland, and 
South Scotland. 
1 Fauna der Gaskohle, vol. i. (1880), pi. xx. See also R. H. Traquair, Geol. 
Mag. [2] vol. viii. (1881), p. 334, and T. Stock, Ann. Mag. Nat. Hist. [5] vol. viii. 
(1881), p. 90. 
