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a few characteristic scales, which are not sufficient for specific determination. 
These scales are completely covered with fine, regular, vertical striae, which 
are as delicate as those on the most delicately ornamented scales of the same 
genus from the English Coal Measures ( Plalysomus tenuis tricitus). So far as 
shown, the striae are not subdivided into tubercles. 
Family — SEMIONOTIDiE. 
Genus — ACENTROPHOltU S, Traquair , 1877. 
(Quart. Journ. Geol. Soc., xxxiii, p. 565.) 
Obs . — This typically Upper Permian genus has not hitherto been 
discovered with certainty beyond the limits of Europe. It occurs in the 
Magnesian Limestone and Marl Slate of Durham, and in the contemporaneous 
Kupferscliiefer of Eisleben, Saxony (Halle Museum) ; hut records of other 
species elsewhere are doubtful and based on imperfect materials. One 
specimen in Mr. Dunstan’s collection, however, exhibits much resemblance to 
Acentrophorns, and may probably be referred to it. This fossil (PI. IV, Eig. 
6) unfortunately lacks the head, and is otherwise too imperfect for specific 
determination, but it is worthy of a brief description. As seen in side-view, 
the back is gently arched, and the maximum depth of the trunk is contained 
nearly three times in the length from the pectoral arch to the base of the 
caudal fin. Traces of the vertebral axis are visible through the thin 
squamation, and there is a vacant space indicating a persistent notochord. 
Each of the haemal arches in the caudal region consists of a single piece, and 
the haemal spines at the base of the caudal fin are especially stout. The 
pelvic fins seem to have been small, and are inserted twice as far from the 
pectoral fins as from the anal fin. The few rays preserved are adpressed to 
the trunk, and lack the fulcra. The remains of the dorsal fin are opposed to the 
space between the pelvic and anal fins, and extend slightly further backwards. 
There is a cluster of large fulcra at the origin of this fin, but the bases of its 
thick rays are seen to be well spaced. The anal fin rays are equally stout and 
somewhat spaced, and their eleven rod-shaped supports can be easily counted. 
The greater part of the caudal fin is destroyed, but appearances suggest that 
the upper lobe of the caudal pedicle is as much shortened as in Acentrophorns. 
Although the scales are only represented in the fossil by a ferruginous stain, 
