302 Mr. F. M^Coy on some new Ichthyolites 



portion of length to width reversed ; I am doubtful about their 

 surface, but the impressions seem distinctly though minutely and 

 irregularly granulated. 



Rare in the old red sandstone flags of Orkney. 



[Col. University of Cambridge.) 



Chirolepis velox (M'Coy). 



Sp, Char. Very slender; head slightly longer than the greatest 

 depth of the body at the base of the pectorals, but less than 

 one-fifth the entire length of the fish ; body tapering gradually 

 from the head ; tail deeply forked, lobes narrow ; pectorals very 

 large, broadly rounded, height two- thirds the depth of the 

 body at their base ; ventrals nearly equalling the pectorals in 

 length, and two-thirds their height ; there is only one-third of 

 their length interval between those fins ; at the same distance 

 behind the ventral is placed the large triangular anal ; it is 

 larger than the dorsal, which is scarcely one-third of its length 

 posterior to it ; both of those fins exceed in height the depth 

 of the body at their base, and are more than their own length 

 in advance of the caudal ; scales very convex, rhomboidal, 

 diagonally sulcated, four in the space of one line. Length 

 9 inches. Fulcral scales of tail very slender, from 2 to 3 lines 

 long and about |^rd of a line wide. 



From its slender form, veiy large fins and forked tail, this 

 would seem to have been one of the swiftest-swimming fishes of 

 the Old Red period, and the above specific name will remind the 

 ichthyologist of those characters. Its lengthened body and small 

 head* distinguish it from all of the genus except the C. uragus 

 (Ag.), from which it differs in the great size of all the fins, their 

 height in proportion to the depth of the body, the deeply forked 

 tail, and the dorsal and anal fins being so far removed from the 

 caudal. (Described from two beautifully perfect specimens.) 



Old red bituminous flags of Orkney. 



[Col. University of Cambridge.) 



Chirolepis curtus (M'Coy). 



Sp. Char. Short, fusiform, mouth very oblique ; head very large, 

 nearly one-third the entire length of the fish ; body rapidly 

 tapering from the head to the tail which is very small, and 

 with a shallow concave posterior margin ; fins small, ventrals 

 nearly three times longer than high, reaching to the anus, 

 where the anal begins ; the anal is about twice the height of 

 the ventral fins, and not quite so long, rather less than its own 

 length in advance of the caudal ; the dorsal is slightly less in 

 all directions than the anal, and is about one-third of its 

 length behind it; scales rhomboidal, four in the space of one 

 line, each with a long, prominent, oval tubercle in the middle. 



