FISH OF THE OLD RED SANDSTONE. 35 



parallel with the posterior margin (some of those on the tail 

 are diagonally sulcated in the direction of the length of the 

 fish). 



In the form and position of its fins this much resembles the 

 C. Cummingice (Ag.), from which it differs in its larger head, 

 more oblique mouth, smaller tail, and much shorter and more 

 rapidly tapering body and tuberculated scales ; by the latter cha- 

 racter it approaches the C. Traillii (Ag.), from which it differs in 

 the position of its fins, and equally with the C. Cummingice (Ag.) 

 in the other characters mentioned above. Length 7^ inches, 

 greatest depth of body 1^ inch. Fulcral scales broad, oval, 

 2 lines long and |ths of a line wide. 



Rare in the old red sandstone of Lethen Bar. 



{Col. University of Cambridge.) 



Chirolepis macrocephalus (M'Coy). 

 Sp. Char. Body thick, fusiform ; tail short, abruptly narrowed 

 from behind the anal fin to half the depth of the body at the 

 pectorals ; head very large, nearly one-third the entire length ; 

 teeth nearly equal, conical, pointed, width of the base two- 

 thirds of the height, their bases nearly in contact ; pectoral 

 fins narrow, oval ; ventrals nearly central, of moderate size, 

 half their length distant from the anal, which is triangular, 

 its height two-thirds its length, although less than half the 

 depth of the body at its base ; the dorsal is only two-thirds 

 the length of the anal, but its height slightly exceeds its 

 length ; its anterior extremity is vertically over the middle of 

 the anal fin, the posterior extremity extending slightly be- 

 hind the extremity of the anal ; caudal very large, deeply 

 forked, but the upper lobe twice the length of the lower ; ful- 

 cral scales very slender, about half an inch long and half a 

 line wide, granulated ; scales rhomboidal, four in the space of 

 one line, gibbous, strongly sulcated diagonally except at the 

 posterior angle. Total length 11 inches. 

 The great proportional size of the head distinguishes this from 

 all its congeners except the C. curtus (M'Coy), from which it 

 differs in the form and position of its fins, large tail, and dia- 

 gonally sulcated scales. 



Rare in the old red sandstone of Orkney. 

 ( Col. University of Cambridge.) 



[Saurodipteridce.) 



Diplopterus (Ag.). 



M. Agassiz has described the species of this genus as having 



heterocercal tails, and in his 'Monog. des Poissons Foss. du 



Vieux Gres Rouge ' he gives a restored figure of the genus with 



c2 



