THE ANNALS 
MAGAZINE OF NATURAL HISTORY. 
[FOURTH SERIES. ] 
No. 88. APRIL 1875. 
XXX.—On the Structure and Systematic Position of the 
Genus Cheirolepis. By R. H. Traquarr, M.D., F.G.S., 
Keeper of the Natural-History Collections in the Kdin- 
burgh Museum of Science and Art. 
[Plate XVII.] 
THIS very interesting genus of Devonian fishes was originally 
described by the late Prof. Agassiz, in the second volume of 
his ‘ Poissons Fossiles,’ p. 178, and was then included by 
him in his family of “ Lepidoides.” ‘The first step towards the 
breaking-up of that heterogeneous assemblage was taken by 
Agassiz himself, in the course of the publication of the same 
great work, when he constituted the family of Acanthodide 
for the genera Chetracanthus, Acanthodes, and Chetrolepis ; 
and this classification was retained in his special work on the 
Fossil Fishes of the Old Red Sandstone. The founder of 
fossil ichthyology seems, however, to have had but a slight 
and not very correct conception of the structure of the fishes 
with which he associated Chetrolepis, as may be seen both 
from his restored figures and his remark that, as the bones 
which he had been able to distinguish in Chetrolepis, “ such 
as the frontal, humerus, temporal, have the same structure 
as in ordinary osseous fishes,” one may conclude ‘that the 
Acanthodians in general had a complete osseous system, and 
not merely a chorda dorsalis as in the Coccostet and other 
fishes of the same epoch” *. Subsequent investigations into 
* Poissons Fossiles du vieux Grés Rouge, p. 44. 
Ann. & Mag. N. Hist. Ser. 4.- Vol. xv. 
