RAVEN. 79 



Among British Birds I have found no examples with 

 three pair, or four pair of muscles, at the inferior larynx ; 

 I proceed, therefore, to the consideration of the most com- 

 plex organ, that furnished with five pair. 



The birds included in this division are all those of the 

 family of the Crows, the Starling, the Thrush tribe, the 

 Warblers, Larks, Buntings, Finches,* Swallows, &c., the 

 organs of voice in which vary only in size. In birds pos- 

 sessing powers of song, or imitation, the tube of the trachea 

 is nearly uniform in shape throughout, the bronchiae long in 

 proportion, and both parts perfectly flexible. The fourth 

 group here introduced exhibits, fig. 1 , a front view fig. 2, 

 a back view and fig. 3, a side view of the lower portion 

 of the trachea and its muscles in the Raven, which may be 

 considered the type of this form, and from its size admits 

 of clear explanation. Figures 2 and 3 of the second group, 

 page 75, exhibit an outside and inside view of the same 

 part, but divested of its muscles, to show by the prevalence 

 and interposition of membrane, the degree of alteration the 

 various muscles are able to efiect. 



Referring again to the fourth group, on the following 

 page, the pair of muscles which descend on the outside of 

 the trachea, divide at a short distance above the end of 

 the tube, and one portion is directed in continuation down- 

 wards and backwards, to be inserted upon the extreme 

 posterior end of the first bone of the bronchia, and is 

 marked/. Its counterpart passes from the place of sepa- 

 ration downwards and forwards to be inserted below the 

 extreme point of the last bone of the tube, and is marked e. 

 Within the angle formed by the separation of these two 



* The Canary is a true Finch, possessing, like the best Song Birds, five 

 pair of true muscles of voice, and hence arises its power of imitating other 

 sounds, as evinced in the Canary, which, some years since, formed an in- 

 teresting subject of exhibition in London. 



