540 
ACIIXOPTERYG1I. 
Type. Imperfect fish ; Newcastle-upon-Tyne Museum. 
A very small species, with the trunk much deeper than long. 
Dorsal and ventral scales granulated, those of the middle of the 
flank having the tubercles fused into delicate vertical striations. 
Form. <$f Log. Coal-Measures: Northumberland. AK clc. „ 
41631. Small pterygoid bone; Newsham, near Newcastle-upon- 
Tyne. Presented by T. P. BcirJcas , Esq., 1869. 
P. 4796. Similar but smaller bone ; Newsham. 
Presented by Sir Richard Owen , K.C.B., 1884. 
The pterygoid or splenial bone of an undetermined species of 
Cheirodus has also been recorded from the Upper Carboniferous 
Limestone of Richmond, Yorkshire, by W. J. Parkas, Geol. Mag. 
[2] vol. i. (1874), p. 431; and a similar fossil from the Yoredale 
Rocks of Wensleydale, Yorkshire, now in the York Museum, is the 
type of the genus and species, Hemicladodus unicuspidatus, J. W. 
Davis, Quart. Journ. Geol. Soc. vol. si. (1884), p. 620, pi. xsvii. 
fig. 24. 
A tooth from the Coal-Measures of Ohio is briefly noticed under 
the name of Cheirodus acutus , J. S. Newberry, Proc. Acad. Nat. Sci. 
Philad. vol. viii. (1856), p. 99. 
Scales from the Carboniferous Limestone of Abden, Fifeshire, now 
in the Edinburgh Museum, are also noticed under the name of 
Cheirodus crassus, R. H. Traquair, Proc. Roy. Soc. Edinb. vol. xvii. 
(1890), p. 400. Similar scales are recorded from Eeith, Ayrshire. 
Genus CH£SIRODOPSIS 9 Traquair. 
[Trans. Roy. Soc. Edinb. vol. xxx. 1881, p. 56.] 
Trunk deep, the dorsal and ventral margins gently convex. 
Head and dentition as in Cheirodus. Pectoral and pelvic fins small. 
Rays of median fins with distant articulations and distally bifur¬ 
cating ; fulcra present. Dorsal fin arising considerably behind the 
middle point of the back, high and acuminate in front, elongated ; 
anal fin similar, but smaller, opposed to the hinder portion of the 
dorsal; caudal fin cleft. Scales very deep and narrow, with re¬ 
latively broad overlapped anterior border, and the exposed portion 
ornamented with a coarse “ tuberculo-corrugate ” pattern, which 
passes into prominent serrations at the hinder border; anterior inner 
keel thick, and peg-and-socket articulation well developed. 
