MAMMALIA. 



Whalebone- 

 whales (Balanoi- 

 dea). In the em- 

 bryo whales of this 

 group minute teeth 

 are present. They 

 are absorbed before 

 birth, and after it 

 their place is taken 

 by baleen, or plates 

 of whalebone, that 

 grow out and hang 

 down upon each side 

 in from three to four 

 hundred plates, like 

 saws on a rack, often 

 attaining a length of 

 ten feet, weighing 

 in all one ton (Fig. 

 336). The outer 

 edges are smooth, 

 the inner frayed into 

 numerous bristles, 

 that form a rude 

 strainer. Ordinari- 

 ly, the lips of the 

 lower jaw cover 

 them, but, when 

 feeding, the enor- 

 mous lips flatten 

 out, presenting the 

 appearance of a 

 scoop Avith whale- 

 bone sides. Into 



this trap myriads of jelly-fishes are swept, becoming en- 

 tangled in the strainer ; when a mouthful is obtained, the 



