Proceedings of the Scientific Meetings of the Zoological Society of London 1870

Page 582

492 DR. J. MURIE ON SAIGA TARTARICA. [June 9, able-sized ploughshare-shaped fatty projections (f.p) meeting in front. External to each fatty mass there is a deep furrow which tends forwards to the anterior thyroid saculus. The posterior half of the laryngeal aperture is walled by the Santorian cartilages (S) and adipose coverings (s.p), the aryteniod cartilages flanking these. There are no lateral sinuses or ventricles other than those de­scribed. The adjoining lips of the rima glottidis forming the true vocal cords are continued down from the fatty eminences for the depth of an inch, and are set at an oblique angle, parallel with, but above the anterior ring of the cricoid. They are smooth-surfaced, and, in the relaxed condition of the parts, approximate, leaving but a narrow fissure. The aperture behind them, at the arytenoid and Santorini cartilages, is a trifle wider; and from these the inferior cavity of the larynx descends as a funnel between the vocal cords, the posterior cricoid shield, and the expanded hinder arch of the uppermost tracheal ring, to the large tracheal passage itself. Thus, as in Hyo­moschus*, there is a partially cylindro-tubular passage behind, more or less divided by the thrust-forward vocal cords from the anterior or upper thyroid chamber. Cleared of superincumbent tissues, the thyroid cartilage (T) ex­hibits two thin but broad and long lamellar alae, and, besides, a median and very remarkable enlarged gibbosity. This salient infla­tion inclines towards, but does not reach, the anterior cricoid arch. The thyro- and crico-hyoid muscles do not cover it, the inner border of the former filling a shallow valley on either side. There is a shallow median notch at the anterior border of the cartilage. Each anterior cornu is about ^ inch long, moderately narrow, and composed of thin translucent fibro-cartilage. The posterior cornua are much stouter and twice the length of the preceding. The upper and lower cornual appendages are situated in a line with each other, though widely apart, and directed contrariwise. At their inner roots the thyroid border is widely emarginate, the lower deeply so, through which passes the cricoid ring and crico-thyroid muscle. The entire surface of the thyroid cartilage is smooth and with no defined oblique line. In extreme length it is 2\ inches, and its greatest dia­meter 1*8 inch. The cricoid (C) is much the stronger cartilage. Its posterior surface is carinate, the broad upper border being transversly arched and free from incision ; the lower border is thin and terminates in a spatular cartilage. The anterior segment of the cricoid ring de­scends obliquely from opposite the postthyroid cornu. At first broadish, and then gradually narrowing, it meets its fellow of the opposite side in the form of an inverted gothic arch, which, ex­panding, overlaps the first and partly the second tracheal rings. The postero-cricoid shield is 2*1 inches long, and 1\ inch broad, and each moiety of the anterior ring is a couple of inches in length. Each arytenoid cartilage (A) is about 1 inch long, and, attached by a joint to the upper and outer angle of the cricoid shield, passes * Flower. P. Z. S. 1867, p. 957.