RVIVIINANTIA. Camelus Bactrianus. — H.
3 in. Thyroid : wings united at an obtuse angle. Cricoid elliptical. Arytenoids gular. Ventricles oval. Epiglottis : apex the epiglottis leading to a sac. A. gutturosa, pomum very large.* Cervus. C. Farandus or Rein Deer. — La rynx has a laryngeal opening at the base of the epiglottis +, leading to a large sac.
C. Alcas. H. 2.5 in. Thyroid : wings united at an obtuse angle ; cornua long ; po mum large, and concave within. Cricoid posterior deep, shielding the five first rings of the trachea ; anterior narrow. Crico-thyroid chink c (fig. 910) broad ; crico-thyroid liga ment strengthened by additional perpendicular fibres d ; its superior ligament absent, inferior inserted into the concavity of the pomum. L. 1.8 in. Voice grave.
obtuse, posterior surface furnished with a tu bercle. Vocal ligaments : superior rather broad bb (fig. 909); inferior strong cc. L. P5 in. Voice grave, but seldom exercised.
similar to the camel. Vo cal ligaments, superior and inferior, present.
ligaments said to be ab sent.
Bos. —Larynx : wings of thyroid nearly equilateral, united at an obtuse angle. Cricoid massive, elliptical. Vocal cords : superior absent ; inferior strong. L. 0.85 in. Trachea 52 rings. Voice sonorous, intense, pitched in C = 256 vib. in 1".
Ovis differs from Bos only in dimensions. Voice guttural, pitched in F = 341 vib. in 1".
Antelope. A. Dorcas, and A. rynx perforated by an aperture at the base of C. H. 1.85 roid: wings united at an obtuse angle. Cor nua : superior long, inferior shorter, curved ; pomum large, concave within. Cricoid, ec centric ellipse. Body : posterior deep, ante rior narrow. Crico-thyroid chink large. L. 1.26 in. Voice grave.
CETAcEA. Bakenoptera 10 in. Thyroid : wings united at a very obtuse angler, the superior margins being nearly straight ; inferior excavated by a triangular notch near the centre. Cornua : superior ab sent; inferior very large, straight, but curved in the dolphin. Cricoid: deep behind, absent in front, where it opens into a large sac § lying in front of the larynx. Tracheal length 4 in. ; posterior cartilaginous, an terior membranous at its laryngeal extre mity. Arytenoids : superior prominences elongated, flattened, and inclined forwards— their inner margins lie in contact ; the inferior prominences short, but strong. Epiglottis : base springs from the superior margin of the thyroid, to which it is fixed by a cartilaginous union. It is flattened and directed back wards to unite with the superior prominence of the arytenoids, with which it completes the aryteno-epiglottic portion of the vocal tube. The diameter of this portion is nar rower than the rest of the tube, which crosses the fauces, enters the posterior nares, and terminates in the olfactory organs. In its
passage it is grasped by a strong sphincter muscle of the fauces, as in the porpoise, e e (fig. 911). Vocal ligaments absent. Aper ture of the vocal tube, in those which have but one opening, as the spermaceti and bottle-nose whales, grampus, dolphin, and porpoise, transverse ; but in those which have two apertures*, as in the great whale bone whale, it is longitudinal. Thyroid gland absent. Voice absent, or reduced to a single lowing. Trachea, in Bakenoptera rostrata, length 4. in.; posterior cartilaginous, anterior membranous at its laryngeal extremity.
vocal organs of birds differ from every other class of animals by the con stitution of the superior, and by the addition of an inferior larynx. The same acoustics apply, with few exceptions, to all Mammalia, but in birds is required an additional investi gation.
The superior larynx of birds is situated immediately below the os-hyoides, to which it is connected by the thyroid membrane, and hyo-aryngeal muscles. Its figure and struc ture are more uniform than those of the inferior larynx. It is partly cartilaginous, and partly osseous.
The thyroid cartilage forms the anterior, and part of the lateral boundary of the larynx, and rests upon the first ring of the trachea. Wings, superior margin ascending forwards and upwards, meet each other in the mesial line, where the cartilage terminates in either a pointed, rounded, or flattened projection; in ferior margin usually horizontal, corresponding to the first ring of the trachea, as in Palmi pedes, but are excavated in Scansores. The posterior margins terminate in two quad rangular bones, with which the thyroid carti lage is frequently ossified (and these then become portions of the wings of the thyroid ; the quadrilateral bones, being also oblique angled, are shaped to form a union with the posterior margin of the thyroid, and present horizontal edges above and below, leaving a small triangular space for the cricoid cartilage posteriorly. The cricoid is a small triangular bone, lying on the inside of the posterior edges of the two quadrangular bones ; it supports the two arytenoid cartilages, as in Mammalia; and although it forms a very small portion of a ring, it is yet necessary for the completion of it. These four bony or cartilaginous pieces are most distinct in young birds, and amongst old ones are quite distinct in the Anas do mestieus and Anas mollissintus, but are con solidated into one in the Scansores, ostrich, and many others. The arytenoid cartilages are long and tapering upwards and forwards, and form by their inner margins laterally the rima glottidis : they are generally ossified. Their external margins are bounded by the thyroid cartilage, and their inner margins form the rima glottidis.