45 



generally applied to the morsels of food vvhilst'held between the 

 inandibles previously to being swallowed. 



«' The cornua of the osfiyoides are I5 inch in length. Thetrachea 

 is 5 inches in length, the rings somewhat flattened and decreasing 

 indiameter tovvards the inferior extremity, from vvliich a singlepair 

 of museles pass ofF to the sternum. The length of the lower fourth 

 of the tube, and the etate of tension in the bronchia, are regulated 

 by a pair of small museles, which, arising from the sides of the tra- 

 cheal cartilages, are inserted into the bone of dlvarication at the 

 extremity of the trachea : and that this part of the tube is subjected 

 to variations in length is indicated by the tortuous character of the 

 recurrent nerves attached to the sides of the trachea at this part. 

 The lungs are small in proportion to the size of the bird, but of the 

 usual form and structure. The abdominal air-cells were of small 

 size. The heart is of a more oblong form than in general ; its 

 apex, as it vvere, truncate ; its length 1 inch. 



" The pectoral museles, as in the PsittacidcB, are but feebly de- 

 veloped, and the keel of the sternum is of moderate size, not pro- 

 jecting more than half an inch from the plane of the bone. The 

 sternum has four notches at its posterior margin. The clavicles, or 

 lateral halves of ihejurcula, are here, as in the Psittacidce and Stru- 

 thionidcp, separate ; they are 1 inch in length, slender, pointed at 

 their lower ends, and joined to each other and to the sternum by 

 ligament only. 



" The peculiar motions of the tail called for a particular exarai- 

 nation of that part. It is difBcult to statė the precise number of 

 the caudal vertebree in consequence of the terminai ones being au- 

 chylosed, requiring for this purpose the examination of a young 

 specimen at a period before the anchylosis takes place. In the 

 skeleton of a black-billed Toucan which I have examined, it would 

 appear that three vertebree are thus anchylosed, making the entire 

 number of coccygeal vertebree nine. The JVoodpecker has also nine 

 caudal vertebree, and this seems to be the greatest number found in 

 Birds. The first six of these vertebree in the Toucan are articiilated 

 by ball-and-socket joints, the ball and the socket being most di- 

 stinct in the two lašt joints. That between the sixth and the an- 

 chylosed vertebree is provided with a capsule and synovial fluid ; 

 the others have a yielding ligamentous mode of connexion. The 

 spinous processes of these vertebree, both superior and inferior, are 

 of moderate size, but smallest in the sixth, where the greatest de- 

 gree of motion takes place. The transverse processes on the con- 

 trary are large and broad so as alraost wholly to prevent lateral 

 motion. The first of the anchylosed vertebree is broad and flat and 

 of a rounded form, supporting the two coccygeal glands : the lašt 

 of these processes is compressed laterally, and of the ordinary 

 plough-share form. The caudal vertebree can be inflected dorsad 

 till their superior spines are brought in contact with the sacrum / 

 in the opposite direction they can scarcely be bent beyond a straight 

 line : and it is to this structure of the bones and joints that is to be 

 attributed the capability in the Toucan of turning its tail upon its 



