OCR Text |
Show 1867.] MR.W. H. FLOWER ON HYOMOSCHUS AQUATICUS. 955 of the Royal College of Surgeons, of the body of a young female Hyomoschus aquaticus, which died in June last, in the Gardens of this Society. The animal was not quite full-grown, the milk-teeth being still in place, with the first and second permanent molars. The various organs were compared during the examination with those of a specimen of Tragulus javanicus of the same age and sex. The tongue is 3\ inches long, and ^ inch in average breadth, rather fleshy, with sides nearly parallel, flat above, and obtusely pointed at the tip. Along the anterior half is a median linear depression. Numerous white, flat-topped, circular, circumvallate papillse are scattered irregularly over all parts of the surface, those at the hinder part being rather larger than the others. Quite at the root is a group of large, closely set, sharp-pointed, conical papillse. These seem to be of the same class as the minute pointed papillae with which the entire surface of the organ is beset developed to an unusual degree. On each side of the upper surface, near the posterior end, is a long, narrow, and deep groove, j3^ inch in length, placed obliquely, so that the posterior end inclines towards the middle line. The edges of this groove are thickened, white, and free from papillae ; and within it is a linear papillary elevation, with a faintly notched free border, projecting slightly above the level of the surrounding parts. This, which appears to be a modification of a circumvallate papilla, occurs also in Tragulus javanicus. The larynx presents a peculiarity in its construction which is not met with in Tragulus, or, as far as m y knowledge extends, in any other ruminant. The whole organ is remarkably large and prominent- a circumstance mainly caused by the extraordinary development of the thyroid cartilage (a, fig. 1, p. 956). This is formed as usual, by two broad lateral plates united at a very salient angle in front. The entire length of the cartilage in the middle line is ly7^ inch. Its upper border has three distinct triangular projections-one in the middle line, broader and shorter than the others, and one on each side, attached to the inferior cornua of the hyoid. The lateral margins, j8-ff inch in length, are gently and regularly excavated, and terminate below in a short, pointed triangular process for articulation with the cricoid cartilage. Below this point the thyroid is continued downward; and instead of being open below as usual, its sides are united across the middle line, so as to form a considerable, rounded, compressed pouch, placed in front of the commencement of the trachea. In Tragulus javanicus the whole vertical depth of the thyroid is but y3^ inch, and it is widely open below, and presents no anterior prominence. In the larynx of the Sheep there is a well-marked projection of the anterior edge of the thyroid rather below the middle hut offering only a slight indication of that which is so remarkably developed in Hyomoschus. The cricoid cartilage (b) forms a strong shield behind, -7- inch in length, and the same in breadth. Its thickened upper margin is hollowed in the middle line, and on each side presents a large oblique |