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Show 162 DE. ST. GEOEGE MIVAET ON THE [Mar. 5, The following papers were read :- 1. On the Hyoid Bone of certain Parrots. By ST. G E O B G E MIVABT, F.R.S. [Eeceived March 4, 1895.] Distinctive structural characters are so much needed for the classification of birds, that I think the following descriptions and illustrations of some skeletal structures, which, so far as I know, are now described and figured for the first time, will not be unwelcome to Ornithologists, if not to other naturalists also. The structure of the hyoid in certain birds was described as long ago as 1835 by G. L. Duvernoy (Mem. de la Societe d'Hist. nat. de Strasbourg, tome ii.), who figured those of Ara ararauna and Coracopsis vasa. In 1858 C. Giebel (Zeitsch. gesammt. Naturwiss. Band xi. pp. 42 & 43, Taf. v. & vi. figs. 35-41) gave representations and descriptions of the hyoid of the following species as named by bim:-Psittacus rufirostris (fig. 35), P. erithacus (fig. 36), P. ochrocephalus (fig. 37), P. leucocephalus (fig. 38), P. menstruus (fig. 39), P. sinensis (fig. 40), and P. cristatus (fig. 41). Dr. Gadowr (1891) has also described and figured (Bronn's Thier-reich, Band vi. Abtheilung iv., Anatomischer Theil, pp. 298, 299, and 302, plate xxx. fig. 20) the hyoid of a species of Ara, Having lately directed m y attention to the skeleton of the Lories, I was very desirous to examine the hyoid in species of that family, in order to compare them with that of Psittacus erithacus, taking the latter as m y type of Parrot-structure. Through the kindness of our Prosector, Professor Beddard, F.E.S., I have received for examination the hyoid bones of Psittacus erithacus, Lorius domicella, L. fiavopalliatus, Eos reticulata, E. indica, Trichoglossus ornatus, and Stringops habroptilus. So far as I have been able to ascertain, the whole order PSITTACI is distinguished from every other order of birds by the shape of its hyoid. The characters which, when taken together, seem distinctive are:- (1) Basihyal much broadened posteriorly. (2) Basihyal developing on either side a forwardly and upwardly directed process, which I propose to distinguish as a para-hyal process. (3) A n os entoglossum in the form of a single broad bone with a considerable central foramen or, much more commonly, in the form of two lateral parts, entoglossals, medianly united in front by cartilage and leaving a vacant space between this and their attachment behind to the basihyal. The real nature of these entoglossals (as I propose to call them) is not evident to me. OwTen writesT of the ceratohyal as being 1 Anat. of Vertebrates, vol. ii. p. 57. |