116 COMPAPJSOXS OF STRUCTURE IN ANIMALS. 



bony network, or cancellated structu^'c, is evi- 

 dently an organ of touch, being endowed with 

 great sensibility. TLrongliout its internal can- 

 cellated structure branches of the fifth pair of 

 nerves freely ramify, and the external horn of 

 the back is so thin, notwithstanding its firm- 

 ness, as rather to defend these nerves than 

 intercept their reception of impressions. In 

 these birds, the tongue is long, slender, flat, and 

 horny, and furnished on each side with short 

 processes like the vane of a feather. With this 

 tongue the toucan often touches the food held 

 between the two mandibles, and with apparent 

 pleasure ; consequently, Ave cannot but regard it 

 as endowed with more sensibility than its struc- 

 ture Avould lead us to suppose. Fruit, eggs, 

 and small birds form the food of the toucan. 



Very different in structure are the beak and 

 tongue of the parrot from those of the toucan. 

 The beak is strong and soUd, and the upper 

 mandible freely movable; the tongue is thick 

 and fleshy. That the latter is gifted with the 

 sense of touch no one who has watched the 

 mode in which these birds take their food can 

 for a moment doubt. If Ave give a parrot a 

 pod full of -fresh peas, we may see with Avhat 

 address, holding the pod in orte foot, it extracts 



