Catalogue of the fossil fishes in the British Museum (Natural History) .. . Two dorsal fins. Clavicular bones absent Ischnacanthidje (p. 20). Clavicular bones present Diplacantbtd^ (p. 22). PART II. B 4 ACANTHODTI. Family ACANTHODID^E. A single dorsal fin present, both this and the anal with ananterior spine. Clavicular bones absent. Synopsis of Genera. A. Teeth minute or absent. Dorsal fin not in advance of anal Acantkodes (p. 2). Dorsal fin in advance of anal Cheiracanthus (p. 16). B. Teeth large. [Arrangement of fins unknown.] Acanthodopsis (p. 15). Genus ACANTKODES, Agassiz. [Poiss. Foss.
Catalogue of the fossil fishes in the British Museum (Natural History) .. . Two dorsal fins. Clavicular bones absent Ischnacanthidje (p. 20). Clavicular bones present Diplacantbtd^ (p. 22). PART II. B 4 ACANTHODTI. Family ACANTHODID^E. A single dorsal fin present, both this and the anal with ananterior spine. Clavicular bones absent. Synopsis of Genera. A. Teeth minute or absent. Dorsal fin not in advance of anal Acantkodes (p. 2). Dorsal fin in advance of anal Cheiracanthus (p. 16). B. Teeth large. [Arrangement of fins unknown.] Acanthodopsis (p. 15). Genus ACANTKODES, Agassiz. [Poiss. Foss. vol. ii. pt. i. 1833, p. 19.] Syn. Acanthoessus, L. Agassiz, Neues Jahrb. 1832, p. 149. Holacanthodes, E. Beyrich, Monatsb. Berl. Akad. 1848, p. , K. H. Traquair, Geol. Mag. [3] vol. v. 1888, p. 511. Body elongate, tapering, and laterally compressed. Teeth minuteor absent; orbit with ring of four circumorbital plates. Pectoralfins very large ; pelvic pair smaller. Dorsal fin remote, neverarising in advance of a point opposite the anal fin-spine. , Fig. Restoration of Acantkodes wardi, Egert.—Coal-Measures, England andScotland. This, the type genus of the family and order, has been morethoroughly investigated than any of the allied genera \ It thusseems advisable to summarize the known facts in the anatomy of thefish, 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 themouth correspondingly wide. The orbit is placed far forwards, andthe upper jaw evidently projects somewhat in advance of the cartilage of the cranium and jaws is partially strengthened by 1 See especially the memoirs of Roetner and Kner, quoted in the synonymyof A. hrovni. ACANTlIODll)^. O minute granular calcifications. There is no definite evidence ofmembrane-bones bordering the mouth ; but in genera which possessteeth ( Acanthodopsis and Ischnacanthus) the o
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