11 
(listance from the base, and then l)i£iircate twice, at the same time hecoming 
jointed hy distant articulations. Eacli pectoral fin comprises not less than 
thirteen rays (PI. Ill, Pig. .3), of which the anterior five are closely adpressed, 
and exhibit an especially long nnjointed base, while the posterior three or 
four are very short and delicate ; each pelvic fm probably had not more than 
six rays (PI. Ill, Pig. 3). The dorsal tin (PL III, Pig. 1), arising at the 
highest point of the hack exactly opposite the pelvic fins, is much deeper than 
long, comprising about fourteen rays, of which the second is longest, and 
nearly three times as long as the hindcrniost ; it exhibits a few large basal fulcia 
continued as a conspicuous series along the front l)order of the fin, and each 
fin-ray is supported hy a distinct, well ossified interspinons hone. The anal 
fin (PI. Ill, Pigs. 1, 3) resembles the dorsal, hut is smaller, exhihiting 
apparently only ten rays. The rays of the caudal fin (PI. Ill, Pig. 1) are 
articulated from a point much nearer to the base than those of the other 
fins, and they are much more numerous than the supporting hnemal spines ; 
a few large deeply imbricating ridge-scales on the atrophied upper caudal 
lobe pass into the conspicuous fulcra of the iqiper margin, wTiile another 
large scale is seen at the base of the lower lobe ; the hinder margin of the fin 
is moderately forked. 
Sqmmatioii . — The aspect of the s([uamation varies considerably in 
diiferent specimens, according as it is exhil)itcd from within or without, in 
ferruginous material or in perfectly hard impression. It is, how^ever, evident 
that the whole trunk is covered with scales, and that those in advance of an 
oblique line from the origin of the dorsal to the origin of the anal-fin are 
comparatively thick, while those behind suddenly become very thin. All the 
scales are rhomhoidal in form, and considerably imbricating, those of the 
dorsal and ventral aspects nearly as broad as deep, while about six principal 
flank-series, at least in the abdominal region, are much deeper than broad. 
The true external form of some of the latter seems to he given in the enlarged 
drawing, PI. Ill, Pig. 4 ; and there are appearances in the ferruginous 
specimens No. c (PI. Ill, Pig. 3), wdiich may ])ossihly he interpreted as 
indicating that these scales were united above and below hy a broad peg-and- 
socket articulation. All the scales (except perhaps the few rhombic scales 
on the atrophied upper caudal lobe) arc externally ornamented at least in 
their hinder portion with nearly parallel, straight, acute ridges, each of which 
usually terminates at the hinder border in a feeble donticulation, and is some- 
times continued in front hy delicate stritu. These ridges, though occasionally 
somewhat radiating, mostly extend in the direction of the long axis of the 
1 ) 
