Pisces. | LOWER PALAXOZOIC VERTEBRATA. 581 
half an inch long and half a line wide, granulated ; scales rhomboidal, four in the space of one line, gibbous, 
strongly suleated diagonally except at the posterior angle. Total length eleven 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 diagonally suleated scales. 
Position and Locality —Rare in the black flags of the Old Red sandstone of Orkney. 
Explanation of Figures.—Plate 2. D. fig. 3. Natural size; 3a, scale magnified twenty-four diameters. 
CHIROLEPIS TRAILLII (Ag.) 
Ref —Ag. Poiss. Foss. t. 1 d. 
Desc.—Length about one foot, greatest depth (behind the pectoral) about three inches; head one-fourth 
the length; dorsal and anal fins equal, higher than long, the former ends at its own length from the caudal 
fin, and its height is equal to two-thirds the depth of body at its base; the anal is half its length in advance 
of the dorsal; ventrals very small, only half the length and height of the anal fin, and placed half-way between 
that and the pectorals, which are also small; scales rhomboidal, about ten or twelve in a quarter of an inch, 
each with a very prominent, sharp, oval, lengthened tubercle in the middle, parallel with the oblique posterior 
margin. 
Position and Locality—Common in the black flags of the Old Red sandstone of Orkney. 
CHIROLEPIS URAGUS (Ag.) 
Ref.—Ag. Poiss. Foss. t. 1c. fig 1, 2, 3. 
Dese.—Length about seven inches, depth one and quarter inch; head one-fifth of the length ; tail 
lengthened, slender, abruptly narrowed from the middle of the anal fin ; anal scarcely half its length in advance 
of the caudal fin, and about one-third of its length in advance of the dorsal; scales rhomboidal, convex, five or 
six diagonal, waved, (?) converging strize on anterior edge, about four in the space of one line; caudal fin very 
obliquely concavo-subtruncate. 
Position and Locality —Old Red sandstone, Orkney. 
CHIROLEPIS VELOX (M*Coy). Pl. 2. D. fig. 2. 
Ref—M Coy, Ann. Nat. Hist. 2nd Series, Vol. IT. 
Desc.—V ery 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 nine inches. 
Fulcral scales of tail very slender, from two to three lines long, and about one-third of a line wide. 
From its slender form, very 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. wragus (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). 
Position and Locality—Rare in the Old Red bituminous flags of Orkney. 
Explanation of Figures—Plate 2. D. fig. 2. Natural size; 2a, scale magnified twenty-four diameters, 
