240 Dr. R. H. Traquair on the Structure 
in 1873, he says :—“ The position of this genus is somewhat 
doubtful; the fulcral armature of all the fins seems to show 
that its place is here as the oldest member of the Lepidosteid 
series ; but its gular plates, which Powrie has pointed out, 
indicate possibly a certain relationship with—descent from (?) 
—the Devonian Polypterini”’*. 
My own observations have been made on a large number of 
examples of the well-known species Ch. Cummingie, Agass., 
from Cromarty, Lethen Bar, and Tynet Burn. Besides the 
specimens in the Edinburgh Museum of Science and Art, 
most of which form part of the Hugh-Miller collection, | 
have carefully gone over the specimens of Chezrolepis in the 
British Museum and in the Museum of Practical Geology, 
Jermyn Street; and I am also specially indebted to the Earl 
of Enniskillen for having, with great kindness, lent me a 
number of excellent specimens from his collection. The care- 
ful examination of these numerous specimens has enabled me, 
I think, to place the question of the systematic position of 
Cheirolepis on a more satisfactory footing than heretofore, 
though it is to be regretted that, on many points of detail, our 
knowledge of the cranial structure of this genus is still rather 
incomplete. 
The key to the whole subject is certainly a knowledge of 
the structure of Palewoniscus and its allies ; and had the writers 
who have previously treated of Checrolepis been better ac- 
quainted with the structural details of that remarkable group 
of extinct fishes, the errors and doubts which have so long 
hung over its affinities would certainly not have prevailed so 
long as they have. The general form of the body, with its 
inequilobate, completely heterocercal tail, the number and 
shape of the fins, with their strongly fulcrated margins, are 
common characters, evident to every one without the assistance 
of the osteology of the head; only the small size, and appa- 
rently non-overlapping character, of the scales seemed for long 
to indicate that its place was with the Acanthodide. The 
scales of Chetrolepis, however, are well known to be arranged 
in very distinct oblique rows or bands, following the same 
general direction from above downwards and backwards as in 
rhombiferous Ganoids generally, and meeting in acute angles 
along the dorsal and ventral mesial lines. On the continua- 
tion of the body-axis along the upper lobe of the caudal fin, 
however, the direction of these bands is suddenly changed to 
* Dunker und Zittel’s ‘ Paleontographica,’ xxii. erste Lieferung, 
1873, p. 25, note. 
