LECTURE IV. 147 



called Sperma-Ceti AVhaleSj is distinguished by 

 having visible teeth in the lower jaw only, which 

 when, the mouth is closed^ are received into so 

 many open sockets in the upper jaw: an accurate 

 inspection of the upper jaw however proves that 

 there are corresponding teeth in that also, but 

 they are very small, and situated so deep within 

 the sockets as to be totally invisible on a general 

 view. 



The Physeter Macrocephalus, or great Sper- 

 maceti Whale, is not greatly inferior in size to the 

 Great Whalebone Whale or Mysticete, and is of a 

 shape not less uncouth; the head being of so vast 

 a size as at least to equal a third of the length of 

 the whole animal. It is from this Whale, as well 

 as from some others of this genus, that the well- 

 know^n substance popularly known by the name of 

 Spermaceti is obtained. This substance, which 

 in the living animal is a liquid oil, is contained in 

 avast cellular cavity within the head; when ex- 

 posed to the effect of cold air, it concretes into a 

 solid form: it exists in other parts of the animal, 

 as well as in the head, and may be gained from 

 the blubber or common oil by proper preparatibn : 

 in a smaller proportion also it is found to exist in 



