VOICE. 



1487 



merely as bellows, the trachea or pipe, and 

 the larynx* or reed. The nervous and mus- 

 cular systems are similar to those of man, and 

 do not require to be treated in detail. The 

 acoustic principles of the first section will 

 generally be applicable to the lower orders of 

 Mammalia, so that when the structure is given 

 the functions will be understood. 



In the account of the anatomy of the vocal 

 organs given by Cuvier, Vicq d'Azyr, Brandt, 

 Wolff, Hcnle, and others, no estimate is made 

 of the relative dimensions of the larynx in the 

 various classes of animals ; therefore, in order 

 that the reader may form an idea of their 

 magnitude in Mammalia, compared with that of 

 man,f it will only be necessary, in those which 

 have a similarity of figure, to give the linear 

 value of one of their dimensions, namely, that 

 of the mean height of the superior margin of 

 the thyroid, above the plane of the base of the 

 cricoid, since their respective magnitudes will 

 be as the cubes of those heights.^ Also the 

 lengths of the inferior thyro-arytenoid liga- 

 ments, when devoid of tension, are given. The 

 letters H and L will be used to represent the 

 heights and lengths respectively. 



QUADRTMANA. The vocal organs of the 

 Quadrumana have already engaged the atten- 

 tion of several distinguished anatomists, such 

 as Vicq d'Azyr, Camper, Hunter, Cuvier, 

 Brandt, and others ; and a condensed view of 

 this part of the subject will be now given. 



Chimpanzee. Os hyoides : base concave, 

 where a sac b (./%. 89-tJ is lodged. Larynx, H. 

 0*8 in. Thyroid : margins, superior and in- 

 ferior, nearly parallel. Cornua short ; supe- 

 rior inclined upwards and backwards, inferior 

 inclined downwards and forwards. Cricoid 

 elliptical: margins, superior triangular, notch 

 in front; inferior parallel to the first ring of 

 the trachea, except in front, where it is de- 

 pressed. Arytenoids small. Cuneiform curved, 

 and in contact with the anterior margin of 

 the arytenoids. Cart. Santorini inferior 

 thyro-arytenoid ligaments prominent. L. 

 0'5 in. to 0'6 in., superior thyro-arytenoid 

 ligament not prominent. Ventricles of Mor- 

 gftgni oval, deep, leading to sac (, a), lying 

 between the epiglottis and arytenoid carti- 

 lage ; right sac anterior to the left, convo- 

 luted, terminating in the concavity of os hy- 

 oides (c). Epiglottis : apex obtuse, trachea 

 16 rings. Voice more acute than in women ; 

 quality inferior: cause, sacculated larynx, &c.* 



* In the following description, the axis of the 

 vocal tube is supposed to be perpendicular to the 

 horizon, and not parallel or oblique, as is generally 

 the case in the living animal. 



t In man, we may assume the mean of H= 

 l\> in. and L=0-72834. 



J In most Mammalia the figures of the larynges 

 are similar; but in some orders they are dissimilar. 

 * r or instance, in the Cerrus, amongst the Ruminantia, 

 thyroid bulges out considerably in front, and in 

 Sus scrofa, amongst the Pachyderinata, it is ex- 

 iH-ly narrow. In the Cetacea the whole larynx 

 lifers from those of all the other orders. 



These measures relate to an animal not quite 

 grown, and are rather too small for an adult 

 impanzee. 



Orang-outang. Larynx : volume equal to 

 chimpanzee. Thyroid ': wings united at an 

 obtuse angle : margins, superior notched in 

 mesial line. Cornua short. Cricoid ellipti- 

 cal : margins, superior and inferior, depressed 

 in front ; the latter connected with the first 

 ring of the trachea. Crico-thyroid chink 

 large. Arytenoids small. Cuneiform large 

 and curved. Cart. Santorini : vocal ligaments, 



Fig. 894. 



Lateral view of the Larynx of the Chimpanzee. 



a, a, sac connected with the lateral ventricles ; b, 

 os hyoides ; c, sac protruding at the base of os 

 hyoides ; d, thyroid ; e, trachea ; /, cricoid. 



inferior prominent; L. less than in woman. 

 Ventricles oval, furnished with a canal pene- 

 trating the thyro-hyoid membrane. Sacs 

 large, lie on each side the larynx. Ventricles 

 valvular, rendering the inflation of the sacs 

 under the control of the animal. Epiglottis 

 broad, apex obtuse.* 



Gibbons. Os hyoides : base not excavated. 

 Larynx, volume nearly equal that in orang; 

 ventricles deep, communicating with a sac in 

 Hylobates agilis, which lies in front on the 

 thyro-hyoid membrane. Voice acute. Cry, 

 bow wow. 



Monkeys of the old continent. Os hyoides : 

 base excavated (fig. 895, B). Sim. Hamadryas, 

 larynx destitute of sac.-f- Larynges perfo- 

 rated, sacs in the thyro-hyoid space. S. cyno- 

 cephalus, S.mona, S. cercopithecus(y?^.895,A), 

 S. Malbrouch, S.^Ethiops, S.rubra, S.Veter J, 



* According to Camper, the laryngeal sacs in the 

 orangs disqualify them from applying the vocal 

 organs to the use of articulate language ; but this 

 hypothesis is untenable, because language is in- 

 dependent of the quality, intensity, or pitch of the 

 laryngeal sounds. 



f Cuvier states that S. Patras has no sac or 

 aperture in the larynx^ this is, however, an error. 

 Cuvier. 



