54 



COMPARATIVE ANATOMY 



there is an enlargement at the projecting end of 

 the glottis, which would seem intended to prevent 

 its retractation ; but this peculiarity does not exist 

 in others. The union of the glottis with the lower 

 aperture of the tube makes a kind of joint to admit 

 of motion, and of dilatation and contraction in the 

 floating palate, in swalloAving, owing to the glottis 

 moving more into or out of the tube. Immediately 

 above the lower aperture, the tube becomes consider- 

 ably larger, and proceeds upwards and forwards, 

 through the bones and soft parts, till it reaches the 

 summit of the head. The tube is usually divided 

 by a septimi into two canals, which in the first sub- 

 division of the ordinary Cetacea open by two blow- 

 holes, whilst in the second the septum ceases, and 

 the tube terminates as it begins, by a single aperture. 

 The whole of this singular mechanism is peculiar to 

 the Cetacea. The other mammalia, when feeding, 

 reside in a medium which, by means of their respi- 

 ratory organs becomes the pahulum vitce, whilst the 

 Cetse in procuring sustinence are habitually under 

 water, which were it to find entrance into their 

 lungs, would prove as noxious as in man ; and yet 

 by a slight alteration in a few cartilages at the top 

 of the windpipe, and in the direction of the air 

 tubes, their feeding in the deep ocean is made as 

 safe for them as that of the others in the balmy 

 breeze. 



Regarding the voice of this order, it would ap- 

 pear that we have not yet arrived at any definite 

 conclusion. Mr. Scorseby states of the Greenland 



