32 FISH OF THE OLD RED SANDSTONE. 



^ Chiracanthus grandispinus (M^Coy). 



Sp, Char. Elongate, fusiform ; tail slender, caudal fin large, mo- 

 derately lobed ; bony spines of the anal, ventral and pectoral 

 fins of great size, their length being about three-fourths of the 

 depth of the body at their base ; the spine of the anal fin is 

 gently curved backwards, those of the ventrals and pectorals 

 straight ; dorsal spine also of great thickness, but its length 

 unknown, situated a little behind the line of the ventrals ; scales 

 rhomboidal, length and width nearly equal, about seven in the 

 space of two lines, convex, strongly striated diagonally in the 

 direction of the length of the fish, one of the diagonal grooves 

 generally much deeper than the rest in the middle. Length 

 from base of pectoral fin to extremity of tail nearly 8 inches, 

 depth of body at base of dorsal fin 2 inches ; pectoral and ven- 

 tral spines nearly IJ inch long and \^ line wide at base, all 

 apparently smooth. 



In the great size and strength of its spines this resembles a 

 great Diplacanthus rather than one of the comparatively feebly 

 armed Chiracanths ; it however has got no second dorsal oppo- 

 site the anal fin, and is clearly a peculiar species of the latter 

 genus, from all the species of which the very large spines and 

 strongly striated scales distinguish it. The branchiostegous rays 

 are very numerous, slender and distinctly ossified ; the cincture 

 supporting the pectorals is very strong and bony. 



Rare in bituminous flags of the old red at Orkney. 



[Col. University of Cambridge.) 



Chiracanthus lateralis (M'^Coy). 



Sp. Char. Slender, fusiform ; dorsal nearly intermediate between 

 the anal and ventral fins, slightly nearer the latter ; spines of 

 the ventral and anal fins very small, slightly curved, not more 

 than half the depth of the body at their base, the dorsal spine 

 about one-fifth longer than the others ; sides of the body im- 

 pressed by a strong, straight, lateral line, rather nearer the 

 ventral than the dorsal margin; scales rhomboidal, a little 

 higher than wide, smooth, each with a vertically diagonal, 

 strong, angular mesial gibbosity, about six scales in the space 

 of one line ; length of anal spine 7 lines, depth of body at base 

 of dorsal 1^ inch. 



I have only seen two tolerably good specimens of this species, 

 which in size and general form both of body and spines resembles 

 closely the C. pulverulentus (M^Coy), from which it is distin- 

 guished by its smaller and more pointed, vertically gibbous 

 smooth scales, and having slightly smaller spines, and the ven- 

 tral and anal spines being proportionally further apart, being 



