ON VOCAL IMITATION, AND VENTRILOQUISM. 



281 



pangolin, and the cetaceous tribes, together with the tortoise, hzards, and 

 serpents ; while others lose their voice in particular regions : as the dog 

 is said to do in some parts of America,* and quails and frogs in various 

 districts of Siberia.! 



It is from the greater or less degree of perfection with which the larynx 

 is formed in the different classes of animals that possess it, that the voice 

 is rendered more or less perfect ; and it is by an introduction of super- 

 added membranes, or muscles, into its general structure, or a variation in 

 the shape, position, or elasticity of those that are common to it, that 

 quadrupeds and other animals are capable of making those peculiar 

 sounds, by which their different kinds are respectively characterized, and 

 are able to neigh, bray, bark, or roar ; to pur, as the cat and tiger kind, 

 to bleat as the sheep, or to croak as the frog. 



The larynx of the bird class is of a very peculiar form, and admirably 

 adapted to that sweet and varied music w^th which we are so often delight- 

 ed in the woodlands. In reahty, the whole extent of the trachea or wind- 

 pipe in birds may be regarded as one vocal apparatus ; for the larynx is 

 divided into two sections, or may rather, perhaps, be considered as two dis- 

 tinct organs ; the more complicated, or that in which the parts are more 

 numerous and elaborate, being placed at the bottom of the treachea, where 

 it divides into two branches, one for each of the lungs ; and the simpler, or 

 that in which the parts are fewer, and consist in those not included in the 

 former, occupyingits usual situation at the upper end of the trachea, which 

 however is without an epiglottis ; the food and other substances being 

 incapable of entering the aperture of the glottis from another contrivance. 

 The lungs, trachea, and larynx of birds, therefore, may be regarded as 

 ! forming a complete natural bagpipe ; in which the lungs constitute the 

 pouch, and supply the wind ; the trachea itself the pipe ; the inferior 

 glottis the reed, or mouth-piece, which produces the simple sound ; and 

 the superior glottis the finger-holes, which modify the simple sound into 

 an infinite variety of distinct notes, and at the same time give them 

 utterance. 



Here, however, as among quadrupeds, we meet with a considerable di- 

 versity in the structure of the vocal apparatus, and especially in the length 

 and diameter of the tube or trachea, not only in the different species, but 

 often in the different sexes of the same species, more particularly, among 

 aquatic birds. Thus the trachea is straight in the tame or dumb swan 

 (anas Olor) of both sexes ; whilst in the male rnusical swan (anas Cygnus)^ it 

 winds into a large convolution contained in the hollow of the sternum. In 

 the spoon-bill (platalea Leucorodia)^ as also in the mot-mot pheasant (pha- 

 sianus Mot-Jiiot)^ and some others, similar windings of the trachea occur, 

 not enclosed in the sternum. The males of the duck and merganser (Anas 



I and Mergus), have, at the inferior larynx, a bony addition to the cavity, 

 which contributes to strengthen their voice. 



Many of the frog genus have a sac or bag in the throat, directly com- 



; municating with the larynx, as the tree frog (^rmia arborea), while the green 

 frog (rana esculenta) has two considerable pouches in the cheeks, which 

 it inflates, at the time of coupling, by two openings close to the glottis. 

 And it is on this account they are able to give forth that kind of croaking 



* Peanant, Arctic Zool. 



iMuller, Collect, of Russian Discoveries, vol. vii. 123. ^ . » 



36 



