2 
ACANTHODII. 
Family ACANTHODIDiE. 
A single dorsal fin present, both this and the anal with an 
anterior spine. Clavicular hones absent. 
Synopsis of Genera. 
A. Teeth minute or absent. 
Dorsal fin not in advance of anal. Acanthodes (p. 2). 
Dorsal fin in advance of anal . Cheiracanthus (p. 16). 
B. Teeth large. 
[Arrangement of fins unknown.]. Acanthodopsis (p. 15). 
Genus ACANTHODES, Agassiz. 
[Poiss. Foss. vol. ii. pt. i. 1833, p. 19.] 
Svn. Acanthoessus, L. Agassiz, Neues Jahrb. 1832, p. 149. 
Holacanthodes, E. Beyrich, Monatsb. Berl. Akad. 1848, p. 24. 
Mesacanthus, K. H. Traquair, Geol. Mag. [3] vol. v. 1888, p. oil. 
Body elongate, tapering, and laterally compressed. Teeth minute 
or absent; orbit with ring of four circumorbital plates. Pectoral 
fins very large ; pelvic pair smaller. Dorsal fin remote, never 
arising in advance of a point opposite the anal fin-spine. 
1 . 
Restoration of Acanthodes wardi, Egert.—Coal-Measures, England and 
Scotland. 
This, the type genus of the family and order, has been more 
thoroughly investigated than any of the allied genera 1 . It thus 
seems advisable to summarize the known facts in the anatomy of the 
fish, and compare some of its more striking features with those pre¬ 
sented by certain members of the Diplacanth family. 
In the head, the suspensorium is oblique and the gape of the 
mouth correspondingly wide. The orbit is placed far forwards, and 
the upper jaw evidently projects somewhat in advance of the lower. 
The cartilage of the cranium and jaws is partially strengthened by 
1 See especially the memoirs of Roemer and Kner, quoted in the synonymy 
of A. bronni. 
