248 On the Systematic Position of Cheirolepis. 
be classed along with Paleoniscus, Pygopterus, Oxygnathus, 
Cycloptychius, and other genera which constitute the long- 
extinct family of Paleoniscide. So close indeed is the corre- 
spondence between the general organization of Cheirolepis and 
ot Paleoniscus, that at most only the distinction of a separate 
“subfamily ” can be accorded to it, in virtue of the peculiarity 
of its scales. Though the precursor of a numerous tribe of 
most interesting fishes in the Carboniferous and Permian eras, 
and which finally disappear with the Lias, Chetrolepis stands 
alone in the Devonian fauna, so far as that has been as yet 
revealed to us*; and no peculiarity of its structure throws the 
smallest additional light on the evolution of the group to which 
it belongs; for the absolute divergence in all other points 
of structure utterly excludes the idea that its minute scales 
betray any special affinity to the Acanthodians, while the 
correct determination of the plates, which have been mistaken 
for jugulars, equally forbids any association of it with the 
“contemporaneous Polypteride.” 
EXPLANATION OF PLATE XVII. 
Fig. 1. Represents the mandibles and branchiostegal rays of both sides 
ot Cheirolepis Cummingia, also the right maxilla and part of the 
circumocular ring. From a specimen from Lethen Bar, in the 
collection of the Earl of Enniskillen. 
. Both interclavicular bones, with the left clavicle and the lower 
extremity of the right clavicle. From a specimen from Cro- 
marty in the Hugh-Miller collection, Edinburgh Museum of 
Science and Art. 
Fig. 3, Outline of the shoulder-girdle and its component bones, restored. 
Fig. 4. A small portion of the edge of the superior maxillary bone, mag- 
nified two diameters. The outer row of small teeth is exhibited, 
also one of the larger ones and the broken stump of another. 
Hugh-Miller collection. 
Fig. 5. Portion of the dentary bone of the mandible of another specimen. 
Along one half of the bone the outermost edge has been broken 
away, thus carrying off the small ones and exhibiting the inner 
row of larger teeth; along the other half this edge remains, 
and shows some of the small teeth, while the continua- 
tion of the row of large ones is concealed by the matrix. The 
working-out of the small teeth has not been so successful here 
as in the preceding specimen. 
Fig. 6. Vertical transverse section of a small portion of the lower lobe 
of the caudal fin, magnified two diameters. 
Fig. 7. Restored outlines of some of the bones of the side of the head. 
The radiating lines on some of the bones are those which, on 
Fug. 
bo 
* With the apparent exception of four species of Acrolepis, described 
by Eichwald from the “Old Red” of Russia (‘Lethza Rossiea,’ vol. i. 
pp- 1578-1581). 
