86 PISCES. 



Palseoniscus (figs. 61, 63). An exclusively Permian gen vis with small 

 fins, regular rhombic scales for the most part united by peg-and-socket, 

 and with minute teeth. The dorsal fin is in advance of the anal. The 

 best specimens are obtained from the Marl Slate of Northumberland 

 and Durham, and from the Kupferschiefer of Thuringia. 



FIG. 63. 



Palaoniscus macropomus ; restoration by E. H. Traquair, nearly one-half nat. 

 size. U. Permian; Thuringia. 



Holurus. Differs from all other Palseoniscids in having the caudal 

 fin obliquely truncated, not forked, while all the fin-rays are simple, not 

 branched, and the fulcra are minute or absent. The scales are sculptured, 

 and there is an enlarged ridge-series between the occiput and the dorsal 

 fin. The typical species, H. parki, is a small fish about one decimetre in 

 length, from the Lower Carboniferous (Calciferous Sandstones) of Dumfries- 

 shire. 



Phanerosteon. Another small Palseoniscid from the same formation 

 and locality as the last, remarkable as being almost or completely 

 destitute of scales on the trunk, while the upper caudal lobe is invested 

 with diamond-shaped ganoid scales. 



Coccolepis. The latest genus of Palaeoniscidse, ranging throughout 

 the Jurassic* period, and remarkable for the deeply overlapping, almost 

 cycloidal scales, which cover the whole of the trunk except the upper 

 caudal lobe and are ornamented with tubercles of ganoine. The upper 

 caudal lobe, as usual, is invested with rhombic scales. Owing to the 

 delicacy of the squamation, the well-calcified endoskeleton of the trunk is 

 usually conspicuous, as already described, and Coccolepis is the only 

 Palseoniscid genus in which the baseosts of the much-extended pelvic fins 

 have hitherto been observed. There are large cutting (lauiary) teeth at 

 intervals in both jaws. The dorsal and anal fins are triangular, the former 

 in advance of the latter; the upper caudal lobe is extremely elongated, the 

 fin deeply cleft and somewhat asymmetrical. The typical species, C. buck- 

 landi, is a small fish about O075 m. in length, from the Lithographic Stone 

 (Lower Kimmeridgian) of Bavaria. Other small species occur in the 

 Lower Purbeck Beds of Wiltshire (C. andreicsi) and in the Lower Lias of 



