and Systematic Position of Cheirolepis. 241 
one from above downwards and forwards—exactly the oppo- 
site; and this change takes place nearly opposite the middle 
of the origin of the lower lobe of the caudal. Though this 
fact is not alluded to by Pander in his description, it 1s most 
distinctly represented in tab. ix. fig. 1 of his illustrations. 
On examining the tail of Palwoniscus, Amblypterus, or any 
allied genera, precisely the same phenomenon is invariably 
seen to occur—viz. the sudden alteration of the direction of 
the oblique bands of scales on the upper caudal lobe to one 
at right angles to that of the bands covering the rest of the 
body*. In Chetrolepis, too, as in these genera, the scales 
clothing the sides of this caudal body-prolongation become 
acutely lozenge-shaped as we trace them on towards the tip 
of the tail. I have not observed in front of the azygos fins 
the peculiar large scales which in most Paleoniscide precede 
the dorsal, anal, and lower lobe of the caudal, ultimately 
passing into the fulcra of these fins; but on the upper margin 
of the tail the arrangement of large V-scales is characteristic, 
and entirely in accordance with that in the heterocercal Lepi- 
dosteids and also in Acipenser and Polyodon. These have 
been so well illustrated in one of Prof. M‘Coy’s figuresf that 
there is no necessity for describing them further in this place ; 
enough has been said to show how strikingly Chedrolepis 
deviates from the Acanthodid in all points connected with 
the scales save their minute size, and how close, on the other 
hand, is the approach which it makes to Palwoniscus in the 
general arrangement of these appendages. And even as 
regards the smallness of the scales, it is to some extent kept 
in countenance by the undoubtedly Paleoniscoid Myriolepis 
Clarket, Egerton, so far as we can judge from the beautiful 
figure given by its eminent describerf. 
The fins of Checrolepis are composed of very numerous rays 
frequently dichotomizing, and divided transversely by very 
numerous articulations; the rays are very closely set, and the 
demi-rays of each side imbricate over each other from before 
backwards, like those of the anal fin of Polypterus, while 
conspicuous fulcral scales serrate their anterior margins. The 
arrangement here is in all essential respects identical with 
* It is an interesting fact that the patch of rhombic scales on the side 
of the vertebral prolongation in the tail of Acipenser and of Polyodon 
(in the latter genus the only scales, along with the “fulera” above them, 
which occur on the body at all) correspond exactly in arrangement with 
this peculiarly arranged caudal patch of scales in the Palzoniscide. A 
similar arrangement is also traceable in the imperfectly heterocercal tail 
of Lepidosteus. 
+ ‘ Paleozoic Fossils,’ pl. 2 b. fig. 5. 
{ Quart. Journ, Geol. Soc. xx. 1863, pl. i. fig. 1. 
