476 CLASS MAMMALIA. 



there are some from seventy to a hundred and twenty feet 

 long. Some species however are considerably smaller. 



The forms of the Balsenee also vary. Some exhibit the 

 shape of an immense and irregular cylinder, the diameter 

 of which is nearly equal to one-third of its length; in 

 others the body appears like two cones pasted together at 

 the bases. The most general form may however be con- 

 sidered an ellipsis more or less perfect. 



The two jaws are not in all instances similarly conformed. 

 Sometimes they are nearly of the same length, sometimes 

 the upper exceeds the lower, and sometimes the lower the 

 upper. Some terminate in a point, and others have their 

 edges rounded and festooned. The aperture of the mouth 

 is sometimes immense. Duhamel-Dumonceau relates that 

 a common whale taken in the bay of the Somme in 1726, 

 though but seventy feet long, had so wide a mouth that 

 two men might enter it without stooping. In some Ror- 

 quals it is said to be so large that fourteen men might 

 stand upright in its interior ; and according to the report of 

 Sibbald, a sloop with all its equipage was seen to enter 

 the open throat of one that had been cast away on the 

 shores of the Great Ocean. 



Both jaws are completely divested of teeth, the place of 

 which is supplied in the upper by certain laminae, called 

 whalebones. Each of these is composed of a kind of stiff 

 hairs or bristles, placed side by side lengthwise. They are 

 united, and, as it were, pasted together by a glutinous sub- 

 stance, which, when dried, produces on each whalebone a 

 smooth and shining surface like scales or horn. They 

 have almost all the properties of this latter substance. 



All these whalebones, taken separately, are of an elon- 

 gated form. They are curved a little in their length like a 

 scythe: they diminish insensibly in elevation and thickness 

 from base to point. Their edge, which is trenchant on the 

 under side, is a little concave. It is furnished from bottom 



