ANIMALS. 227 
and distinct. The scales themselves are large, and of very uniform size over the 
whole body. The specimens hitherto found are not in a condition to show the 
superficial characters of the scales, the impressions of the under-sides alone being 
preserved. The dorsal fin is placed much nearer the tail than in any other species : 
in this respect, but in no other, Palgoniscus catopterus resembles the genus Catopterus 
of Mr. Redfield. The tail is decidedly heterocerque. It is altogether so distinct from 
the other Palgonisc:, that it is recognisable at first sight.” A slab presented to 
the Geological Society by Mr. Green, exhibits, on a surface not exceeding two feet 
square, above 250 specimens. 
Paleoniscus catopterus occurs in a quarry of red sandstone at Rhone Hill, in the 
parish of Killyman about three miles east of Dungannon, Ireland. 
Family PYCNODONTID&, Agassiz. 
Genus Platysomus, Agassiz. 
Ruomsus, Wolfart. 
Stromateus, Blainville. 
URoptTEeryx, Agassiz. 
GuLosuLopus, Minster. 
For the latest published account of this singular genus, and the reasons for 
removing it from the heterocercal Lepidoids to the present family, the reader is 
referred to a very admirable paper by Sir Philip de Malpas Grey Egerton, Bart., M.P., 
inserted in the ‘ Quarterly Journal of the London Geological Society,’ vol. v, part i, 
pp. 329-332. 
PLATYSOMUS MACRURUS, Agassiz. Plate XXVI, fig. 1 a. 
FossIL FISH ; GENUS NOT DETERMINED, Sedgwick. Trans. Geol. Soc. Lond., 2d series, 
vol. ili, p. 118, pl. xii, figs. 1, 2, 1829. 
UROPTERYX UNDULATUS, Agassiz. Msc. Walchner, Geol., p. 270. 
PLATYSOMUS MACRURUS, . Poiss. Foss., vol. ii, p. 170, pl. xviii, figs. 1, 2. 
= == as Morris, Catalogue, p. 202, 1843. 
= — a Rep. 13th Meet. Brit. Assoc., p- 198, 1844. 
=e — ue De Verneuil, Bull. Soc. Géol. de France, 2™ serie, 
vol. i, p. 39, 1844. 
Lt = a Geol. Russ., vol. i, p. 227, 1845. 
= — as Tennant, Strat. List, p. 89, 1847. 
= — : King, Catalogue, p. 15, 1848. 
— = Pes Howse, Trans. T. N. F. C., vol. i, p. 234, 1848. 
== = ne Egerton, Quart. Journal Geol. Soc., vol. y, part i, 
p- 329, fig. 1, 1849. 
This appears to be one of the rarest of the Fishes of the Permian System. When 
Agassiz was engaged upon his great work on ‘ Fossil Ichthyology,’ he had not an oppor- 
tunity of examining the then unique specimen from East Thickley, figured in the ‘ Transac- 
