OCR Text |
Show 1902.] PLECTOGNATHOUS FISHES. 295 A. 28 32), whilst the frontals have large postero-lateral expansions, completely roofing-in the post-frontals, which are invisible from above. [Since the reading of this paper I have been in communication with Dr. Pellegrin of the Paris Museum, who has examined the skeleton of Xenopterus bellangeri described by Hollard, and also the spirit-specimens referred to that species. These latter he is unable to distinguish from X . naritus Richardson; but the skull figured by Hollard differs considerably from that of X . naritus, and, unless these differences should prove to be sexual, must lie regarded as belonging to a distinct species, although the number of vertebrae (29) and of fin-rays (D. 34, A. 29) are the same in each case. In X . bellangeri the frontals are scarcely thickened, they show lines resembling sutures, corresponding to similar lines in Chone-rhinus modest us Bleeker, and due to the texture of the bone, and Text-fig. 59. Skulls of (A) Chonerhinus mndestus, (B) Xenopterus bellangeri, and (C) Xenopterus naritus, seen from above; in the latter the left postero-lateral extension of the frontal has been cut away. Lettering as in text-fig. 58. their postero-lateral expansions do not extend over the parietals and squamosals. X . naritus differs in having very thick frontals, without any trace of lines of ossification and even the median suture obscure, and with strong postero-lateral expansions roofing-in parietals and squamosals. Through the kindness of Dr. Pellegrin, to whom I take this opportunity of expressing my gratitude for the trouble he has taken, I am enabled to reproduce a drawing of the skull of X . bellangeri already figured by Hollard, for comparison with those of X . naritus and Chonerhinus modestus. Hollard's skeleton must be regarded as the type of X . bellangeri; it is 280 mm. in total length.-Dec. 20, 1902.] |