. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. VOICE. 1503 In Bombmator igncus, Hyla varitcosa, and others, the arytenoid cartilages are regular obtuse-angled, and nearly equilateral triangles. In B. cinereus they are more acute-angled, and directed backwards. The vocal cords in bnfo are very thin elastic membranes, such as might be expected to produce the croaking deep tones of these batrachia. In Plpa the larynx is a very peculiar piece of mechanism ; the arytenoid cartilages being convex externally and concave internally, so that when the entrance to the larynx is
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. VOICE. 1503 In Bombmator igncus, Hyla varitcosa, and others, the arytenoid cartilages are regular obtuse-angled, and nearly equilateral triangles. In B. cinereus they are more acute-angled, and directed backwards. The vocal cords in bnfo are very thin elastic membranes, such as might be expected to produce the croaking deep tones of these batrachia. In Plpa the larynx is a very peculiar piece of mechanism ; the arytenoid cartilages being convex externally and concave internally, so that when the entrance to the larynx is closed they form a dome over the windpipe, which Cuvier has compared to a kettle-drum. In Rana temporaria, R. esculenta, and Hyla, the males are provided with two sacs, which open by a straight canal into the larynx. These sacs are situated on each side of the lower jaw, and are capable of considerable distension, when filled with air during the cry of the animal. Cuvier, Roesel, and Blumenbach, describe only one sac in Hyla ; but Meckel, as well as Henle and myself, found two sacs, as in the other frogs. These sacs doubt- less exert a powerful influence on the quality of the sounds which frogs utter, analogous to the influence of similar sacs which exist in many of the higher animals. Fig. In Proteus angtiinus the most simple form of cartilaginous larynx is found, consisting of lateral cartilaginous strips, divided in two on each side ; the superior portion answering to the arytenoid cartilage of the higher orders of animals, the inferior to the laryngo-trachealis cartilages. In the Triton, and Salamander, the larynx consists of a membranous sac, which is kept open by the lateral cartilages of the vocal tube. Hence we learn that the arytenoid cartilages do not wholly disappear, until the larynx be- comes entirely membranous. INSECTA. — A large number of insects are mute; some produce their sounds merely by friction, and others by the passage of the air through the th
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