OCR Text |
Show 1870.] DR. J. M U R I E ON SAIGA TARTARICA. 493 therefrom in an oblique line cutting the said point and the thyroid gibbosity. It has an irregular elongate triangular figure, | inch broad behind and narrow in front. Its borders and surfaces are more or less concave ; and the cartilage altogether is stout, thick, and from 0*3 inch deep behind lessens considerably forwards. At the external cricoid joint there is a considerable-sized nodosity ; and the inner superior margin is crescentically ridged and overtopped by the cartilage of Santorini. The latter (S) is a thin falcate lamella of soft yellow fibro-cartilage, some 0*8 inch long, and above 0*3 inch in extreme depth. It forms a crest, as said, to the arytenoid, and is itself covered by a fatty layer, producing those posterior elevations of the postlaryngeal aperture (s.q)) already dilated on. It may be that these include the cartilages of Wrisberg, which otherwise are wanting. The cartilage of the epiglottis has a consistence like the last, is of obcordate shape when cleaned of investing membrane, and has a retroverted broader tip than in the Prongbuck. As regards the structure of the Saiga's larynx, it may be regarded as an intermediate type between the Sheep's and that of some Antelopes and Deer. In Oris we have a rudimentary condition or tendency of the thyroid cartilage to inferior enlargement. This becomes more marked in such forms as the Gazella dorcas, G. rufifrons, and Tarandus rangifer, as Meckel* has noted. In Hyomoschus aquaticus this protuberance is increased in dimensions, as Flower f figures, but is not, as he supposes, peculiar to this Ruminant; for, as long ago demonstrated by Pallas, the Antilope gutturosa\ is notorious and specifically named on account of its great thyroid development, which is said, indeed, to produce quite a gular swelling. As figured, this thyroid inflation is several inches in diameter. The single thyroid sacculus contained within, doubtless coexists in these latter forms, as in Saiga, thus differing from several of the Pachyderms' and other types, where there are a pair of lateral sacculi. In the Horse, however, there is a similar recess at the base of the epiglottis. Concerning the voice of the Saiga, if this be studied not purely physiologically, but as a sign indicating affiliation of stock, it is of some interest. The tone and manner of utterance is remarkably like that of a Sheep, to wit, a single full bleat or bay, the shrill treble note of Goats and most Antelopes being markedly varied from that of the above genera. The Deer generally have a more grunting tone, though extensively modified in different genera, as, indeed, also obtains in the Antelope section. Of the muscles connected with the larynx and its bony arch, the sterno-hyoid and sterno-thyroid, long and fleshy, are united opposite the posterior end of the thyroid gland on the fourth cartilaginous ring of the trachea : here they separate ; the former continues in the middle line to the os hyoides, whilst the narrower sterno-thyroid diverges slightly outwards, and is inserted by a short broad tendon into the outer posterior margin of the thyroid cartilage. The crico- * Anat. Comp. vol. x. p. 604. t Loc. cit. p. 9f>.r*. X Spic. Zool. tab. iii. fig. 16. P R O C ZOOL. Soc-1870, No. XXXIII. |