526 On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 
Platycanthus isosceles—Morris and 
Roberts, 1862. -“ Quart. Journ. Geol. Soc.,” Vol. XVIII, p. 101. 
Coceosteus carbonarius, “ 1862. 53 5 ss > Wal SVWI00L, jo, UO, 
Oracanthus milleri—Young and 
Armstrong, 1871. “Trans, Geol. Soc. Glasgow,” Vol. III., Supt. p. 73. 
es minor, 1 1871. 93 50 SS 5 Vol. III., Supt. p. 73. 
milleri—Armstrong, 
Young & Robertson, 1876. “ Catal. W. Scot. Foss.,” p. 62. 
es minor, 1876. - 3 5 la O% 
1 confluens—J. J. Bigsby, 1878. ‘Thesaurus Dev.-Carb.,” p. 309. 
59 milleri, i 1878. . job aweh 
5 minor, 5 1878. 5 yp id OD 
5 pus‘ulosus, o 1878. 35 » Io eoeh 
Asterolepis verrucosa, - 1878. ¥ 5 phe Dosti 
Coccosteus carbonarius, é. 1878. 53 5 Te OHM 
Platycanthus isosceles, * 1878. , » 9 {ob 0S) 
Oracanthus milleri—de Koninck, 1878. “ Fauna du Cale. Carb. de la Belgique.,” p. 69, pl. v., fig. 10. 
In the early part of the present century some specimens of a large Ichthyodorulite 
wvere found in the Black Rocks at Clifton, near Bristol, by Dr. Miller. They were 
deposited in the Bristol Museum, and were named by Buckland and De la Beche, 
Ichthyodorulithes cu: vicostatus, they were not, however, described by these authors. 
They were considered to be the spines of a fish of Elasmobranch type, the specimens 
were of large size, very wide at the basal end, and their exposed surfaces were 
ornamented by prominent pustulations. The base did not exhibit evidence of 
having been so deeply implanted in the integuments as is generally observed in 
other genera. Prof. Agassiz described and gave figures of the specimens in his 
“ Recherches sur les Poissons Fossiles.” ‘The genus Oracanthus was instituted for 
their reception, and the specimens were arranged in three species, being O. pustulosus, 
QO. minor, and the third in honour of its discoverer, O. millere. 
Oracanthus pustulosus is the largest in size, it is described as being very thin, 
much compressed, with a very spacious internal cavity, the external surface is 
covered with tubercles disposed irregularly over the spine and most numerous on 
the inferior margin. O. mulleri is distinguished by the tubercles being arranged. 
in oblique rows or running into each other so as to form irregularly oblique ridges. 
The third species, O. minor, is very small and it is pointed out by Prof. Agassiz, 
that it may have been the point of a larger specimen, but that on comparison with 
the apex of spines of either of the other species he has found that it is very con- 
siderably narrower in proportion to its leneth; its external appearance it is stated 
very much resembles the claw of a crab, but its internal structure certainly indicates 
its position to be in the genus ( racanthus. 
In addition to the three species from the Bristol Limestone, a fourth was dis- 
covered in the Limestone of Armagh, which Prof. Agassiz, named O. confluens, but 
did not describe. 
Prof. M‘Coy, considered that O. confluens was the same species as O. miller?, 
and also that O. minor was simply the point of the spine O. millert?. It is further 
