GREAT NORTHERN RORQTTAL. 129 



generally mentioned by subsequent authors. It 

 consists of a number of longitudinal folds, nearly 

 parallel, which commence under the lower lip, oc- 

 cupying the space between the two branches of the 

 lower jaw, passes down the throat, covering the 

 whole extent of the chest, from one pectoral fin to 

 the other, and somewhat further, and terminates far 

 down the abdomen. It often happens that two of 

 these folds are distinct at their extremities, but form 

 one only in the middle portion. They are of different 

 width according to the size of the individual, varying 

 from half an inch to two or three inches. The 

 external portion of these folds is of the colour of 

 the neighbouring skin, whilst the parts which are 

 usually folded in are of a more delicate appearance, 

 generally of a pale white, and in some species of a 

 beautiful red colour, corresponding to that of the 

 lip. M. Lacepede congratulates himself on having 

 made a great discovery respecting the use of this 

 structure, which suggested itself whilst examining 

 certain drawings which were transmitted to him by 

 Sir Joseph Banks. He supposes it to be a great 

 bladder placed between the branches of the lower 

 jaw, extending far underneath the body ; and con- 

 ceives the whale can fill this pouch with atmospheric 

 air from the spiracles, so as to give it a circum- 

 ference of ten or twelve feet. In short, he considers 

 it as a kind of swimming bladder, by which the 

 animal raises itself at will towards the surface ; and 

 by it he accounts for the extraordinary agility and 

 power it displays, in the pursuit and capture of its 



