On the Cranial Osteology of the Fishes of the Families Osteoglossidae, Pantodontidae, and Phractolaemidae
Journal of the Linnean Society of London Zoology
AN extensive investigation on the structure of the skull of the lower Teleostean fishes which 1 began in the year 1896 has now arrived at a stage of progress that warrants the publication of certain of the results. Two papers have already appeared : one, on the skull of the Elopids and Albulids, in the ' Proceedings of the Zoological Society ' (1904, ii. pp. 35-81), and the other, on the slrull of the Mormyrids, Notopterids, and Hyodontids, in the ' Journal of the Linnean Society' (Zoology,
... iety' (Zoology, xxix. 1904, pp. 188-217). The present communication represents a third installment of the results ; a fourth, dealing with the skull of the Clupeoid fishes, ia rapidly approaching completion. h e n species of' fishes are considered in this paper-three species of Osteoglosszcm*, and one species of each of the genera Arapazrna, Heterotis, Pantodon, and Phractolmmzcs. These fishes are all of freshwater habit, they are all tropical, and, with the exception of Osteoglossurn Leichardti of Queensland, all occur within ten degrees of the Equator. Osteoglosswm bicirrhosum and Arapaima gigas are found only in Brazil and Gtuiana, Osteoglossurn formosum in Borneo and Sumatra, and Heterotis niloticus, Pantodon Buchholzi, and PLractolmmus Ansorgii in Equatorial Africa. One of the most striking and characteristic features of the skull of the Osteoglossid fishes is the occurrence of a paired lateral peg of the parasphenoid bone for articulation with the hyopalatine arch, described by Bridge in Osteog2ossum formosum * The Australian species of Osteoglusszwr was described by Giinther in 1864 under the name of Scleropnges, but he afterwards withdrew the genus, oonsidering his Scleropages Leichardti to be a species of Osteoglossum. Bodenger, however (Ann. Mag. Nat. Hiat. (7) viii. 1901, pp. 514-515), has recently found that Osteoglosszcin bicirrhoszcni diflers from 0. formosum and 0. Leichardti in the number of vertehrs, the position of the pelvio flns, and the number of brancbiostegal rays, and he proposes to re-establish the genus Sckmwgcs for the inolusion of the latter two speciw.