MUTE MAMMALS.

201

Voice of Mammals.-Among mammals some are mute, and yet these are not always deficient in those parts of the larynx which are most essential to voice.

Among the orders which compose the class mammalia, the cetaceans, consisting chiefly of the whale tribe, are often described as mute. These animals, however, are not mute altogether, but possess only a single lowing note, or at the utmost they have the power of simply bellowing. There are two distinct sections of cetaceans. The first includes what have been termed the herbivorous cetaceans, such as the sea-cow, the representative of the popular mermaid, and the dugong. The second order includes the common cetaceans, popularly known as blowers. The act of blowing, from which they derive their name, consists in the expulsion of water by the nostrils; that is, along with their prey they receive a large quantity of water into the mouth, and while the mouth remains closed they blow out this superfluous water by a hole in the upper part of the head.

This expulsion of water is produced by means of a peculiar arrangement of the veil of the palate. The water accumulates in a sac situated at the external orifice of the cavity of the nose, whence, by the compression of powerful muscles, it is violently expelled through a narrow aperture pierced on the summit of the head. By this contrivance these animals throw forth those jets of water which are seen by mariners at a great distance. The larynx has a pyramidal form, and penetrates into the posterior portion of the nostrils to receive air, and conduct it to the lungs, without the animal being obliged to raise its head and mouth above water for the purpose. As there are no projecting laminæ in the glottis, they can hardly be said to have the proper organs of voice, and thus the noise they make may be described as a simple vehemence of expiration.

FIG. 93.

a,

pyramidal position of larynx; c, pha

rynx; d, laryngeal cavities laid open.

The larynx, however, in these animals is highly developed in other respects.

202

VOICE OF RUMINANTS AND PACHYDERMATA.

Among the animals commonly described as mute is the giraffe or camelopard, termed by naturalists Cameleo-pardalis giraffa. In the giraffe the vocal ligaments appear to be absent.

The armadillo (Dasypus) is another of the mammalians described as mute. The only peculiarity of the larynx which has been observed is, that the epiglottis, or valve-like cartilage of the larynx, is bilobed. The armadillo, it will be remembered, is remarkable among mammals for the scaly, hard, bony shell, composed of pavement-like compartments, which cover the head, the body, and even the tail. These animals belong to the order termed Edentata. They live in burrows, which they excavate. To the edentata also belong the ant-eaters (Myrmecophaga), which are regarded as mute. the same order is found the sloth (Bradypus tridactylus). In this animal, however, vocal ligaments are found, and the windpipe is convoluted. The voice is a plaintive melody, consisting of an ascending and descending scale of the hexachord."

In

Among the Rodentia, or gnawers, the common porcupine of Europe is mute. In this animal it has been ascertained that there are no vocal ligaments.

Such, then, are a few examples of the animals in the class Mammalia, which are mute, or nearly mute.

In the order Ruminants we find animals possessed of a sonorous voice, exemplified particularly in the ox. In the ox the larynx is well developed; there are no superior vocal ligaments, but the inferior or true vocal ligaments are strong, and nearly an inch in length; the windpipe consists of nifty-two cartilaginous rings, that is, nearly three times as many as they number in man. The voice is sonorous, intense pitched in C: 256 vibrations in a second.

The sheep belongs to the same order of quadrupeds. The larynx differs from that of the ox only in dimensions. The voice is guttural, pitched in F = 341 vibrations in a second.

To the same order belongs the camel (Camelus Bactrianus). In the camel the larynx is well developed; the superior vocal ligaments are present, and the inferior vocal ligaments are strong. The voice grave, but seldom exercised.

is

In the Pachydermata, or thick-skinned animals, there are many species possessed of a sonorous voice. Among these are the horse, the ass, the hog, the rhinoceros, and the elephant. In the horse the larynx is highly developed, and the windpipe has as many cartilaginous rings as that of the ox. The superior vocal ligaments are not prominent. Above the junction of the proper vocal ligaments, between that and the epiglottis, there is an oval cavity, and on the posterior surface of the epiglottis there is a groove, furnished at its base with a semi-lunar membrane. To this membrane much effect has been ascribed in the production of the peculiar neighing of the

LARYNX OF THE ASS, MULE, ETC.

203

horse. It is doubtful, however, if this peculiar sound be so much dependent on this membrane as has been believed.

In the ass the larynx is also well developed. In the windpipe the rings are spiral. The bray of the ass which seems greatly to depend upon the presence of two large sacs placed between the vocal ligaments and the internal surface of the thyroid-is well known; it has a range of about five tones.

The voice is a

In the mule the larynx resembles that of the ass. species of bray, more resembling that of the ass than the neighing of the horse. The tapir (Tapir Americanus) has some peculiarities in its larynx. It has, however, superior vocal ligaments, which are short and distinct, and inferior vocal ligaments, which are strong. The voice is a species of whistle.

The hog (Sus scrofa) has also some peculiarities in its larynx; its voice, as is well known, is a grunting, discordant sound.

The rhinoceros is remarkable for having the superior vocal cords very prominent.

204

ROAR OF THE LION.

The

In elephants the larynx is largely developed. The superior vocal ligaments are indistinct; the inferior or proper vocal ligaments are strong. The windpipe exhibits thirty rings, which are often partially subdivided, as in the case of the bronchial ramifications. voice, aided by the trunk, is intense, and of a grave pitch. Under the head of Marsupial animals, we find the kangaroo and the opossum.

a

C

A.

FIG. 96.

B.

OF DIDELPHIS OPOSSUM.

In the kangaroo (Macropus major) several peculiarities occur in the larynx. In particular, the vocal cords are membranous, and fold upon themselves, so that they cannot be stretched by the arytenoids. The voice when in pain consists of a piteous

A. LATERAL VIEW OF LARYNX moan. In the opossum (Didelphis opossum) the vocal a, thyroid cartilage; b, cri- ligaments are very short, hence the voice is acute. The

coid; c, crico-thyroid ligament; d, trachea.

B. POSTERIOR VIEW OF THE Opossum purrs like a cat.

SAME.

In the order Carnivora we c, cricoid; e laryngo-tra- find examples of animals with cheal ligament; d, trachea. intense voice.

FIG. 97.

In the lion (Felis leo) the larynx is well developed; the vocal ligaments, both superior and inferior, are present; the superior being prominent. The ventricles of the larynx are deep, forming a sac between the upper and under vocal ligaments. The windpipe is possessed of fifty cartilaginous rings. The voice is grave, highly in- a, tongue; b, epiglottis; tense, the roar terrific.

LARYNX OF CAT.

c, superior vocal cords; d, inferior vocal cords.

The tiger (Felis tigris) has a larynx resembling that of the lion, the superior vocal ligaments being very prominent. The voice of the tiger is more acute than that of the lion. It purrs like the cat. The leopard and the cat belong to the same genus. Felis leopardus and Felis catus. These two animals, like the rest of the feline tribe, have the superior vocal ligaments well developed. It is supposed that by these superior vocal ligaments the purring sound is produced. The voice of both animals is a mewing-they have by night a melancholy cry.

In the order Quadrumana, to which the apes and monkeys belong, the essential form of the organ of voice does not vary much, but

VOICE OF THE APES, MONKEYS, AND BIRDS. 205 peculiarities occur in the resounding walls. Thus in the ourangoutang a sac exists between the thyroid cartilage and hyoid bone, and in the mandrill, pavian, and macacos, membranous sacs are observed below the hyoid bone. In the Myceti, or howling apes of the New World, the apparatus for the resonance of the voice is greatest. In these the hyoid bone and the thyroid cartilage are expanded in such a manner as to contain large cavities, which open into the ventricles of the larynx, and besides this there appear to be sacs common to the larynx and pharynx. Further, the epiglottis in these apes has a very large and peculiar form. In the Sapajous (Ateles and Cebus) a curved tube is formed by the increased size and altered forms of the epiglottis, and some adjacent structures. The voice of these animals has a whistling character.

In the chimpanzee the true vocal ligaments are prominent. The windpipe has sixteen rings. The voice is more acute than in women; its quality inferior, owing probably to the sacculated larynx. In the ourangoutang the inferior vocal ligaments are prominent, but not so long as in the families of the human race. The ventricles are valvular, so that the inflation of the peculiar sacs is under the control of the animal.

In the Gibbons the ventricles are deep, and communicate with a sac.

FIG. 98

The voice is acute; the cry "bow LATERAL VIEW OF LARYNX OF CHIMPANZEE. Wow."

aa, sac connected with the lateral ventricle: b, hyoid bone, with c, sac protruding at its base; d, thyroid; e, trachea; f, cricoid.

In the monkeys of the old continent there are also laryngeal sacs. These sacs modify the quality of the voice, giving to it, even when acute, a peculiar hoarseness. In the Simia appella and Simia capucina, there are some peculiarities in the structure of the channel for the passage of air. The voice in quality is like that of a flute; hence these are called whistling apes, and, from the peculiar expression of this whistle, which is a plaintive melcdy, they are termed weeping apes.

Voice of Birds.-The great peculiarity in the organs of voice among birds is the inferior larynx; that is, birds, in addition to the larynx corresponding to that possessed by mammals, have one peculiar to themselves at the inferior extremity of the windpipe. Even the superior larynx of birds differs considerably from the larynx in