356 On the Fossil Fishes of the Carboniferous Limestone Serres of Great Britain. 
nearest the point; straight: transverse section somewhat triangular, diameter 
from anterior to posterior surface rather greater than that between the postero- 
lateral angles. Anterior surface rounded; lateral surfaces slightly depressed, 
especially towards the postero-lateral angles. The whole of the anterior and 
lateral surfaces are strongly tuberculated, the tubercles arranged diagonally in 
parallel rows across the spine; they are large along the front and for two-thirds 
of the breadth of the sides, the remaining third nearest the back of the spine on 
each side is covered with minute tubercles without definite arrangement. The 
larger tubercles are slightly elevated on a bony pedestal, the upper surface thickly 
coated with ganoine. A deep circular groove extends along the posterior surface. 
The junction of the posterior and the lateral surfaces is produced to form a broadly 
rounded angle coated thickly with ganoine, slightly raised here and there into 
minute tubercles. 
This species differs from Cosmacanthus maleolmsoni, Ag., from the Devonian rocks 
(‘ Poiss. Foss. du vieux grés rouge,” tab. 33, fig. 28), in the presence of the thick 
rounded mass of ganoine which invests each of the latero-posterior angles. | From 
Cosmacanthus carbonarius, M‘Coy (“ Ann. Mag. Nat. Hist.,” Second Series, Vol. IT., 
p. 119), described as having the posterior suleus very wide and rounded “ being 
bounded by the last lateral row of tubercles on each side. A fragment 1 inch 
8 lines long and 23 lines wide at the narrow end, increases at the rate of nearly 
2 lines in an inch.” This species is distinguished also by the presence of the posterior 
margin of ganoine, by the shallow posterior sulcus, and its very slight decrease in 
diameter from the base upwards. 
Except that there are no denticulations along the postero-lateral angles, this genus 
appears to bear a close relationship to that of Lepracanthus (Ag.) from the Coal 
Measures. 
Formation and Locality ; Carboniferous Limestone, Armagh 
Hex coll. Enniskillen, 
Cosmacanthus carinatus, Davis. 
(Pl. XLVIIL, fig. 4.) 
Fin-spine, very slightly curved along anterior margin, posterior straight, 
1°5 inches in length, ‘15 in greatest breadth at the junction of the base and exposed 
part. Base tapering. Exposed part ensiform, ending in an acute point. In 
transverse section the spine is an obtuse-angled triangle, the diameter of the 
posterior portion being greater than from back to front. The lateral surfaces are 
thickly covered with ganoine-coated tubercles. The tubercles when magnified 
present a most peculiar appearance : rising on a stem from the surface of the spine 
to one and a half times their diameter, they become spread out or extended towards 
the base of the spine ; the surface of the tubercle in this direction is denticulated in 
