THE ORDER CETACEA. 23 



The young one continues under maternal protection 

 for probably a year or more, or until, by the evolution 

 of the whalebone, it is enabled to procure its own 

 nourishment. The notches in this substance (the ba- 

 leen) have been supposed a criterion of age ; by which, 

 if correct, it would appear that the whale reaches the 

 magnitude called by the whalers size (i. e. with a six 

 feet of whalebone) in twelve years, and attains its full 

 growth at the age of twenty or twenty-five. 



Every species of the whale genus propagates with 

 only those of its own species ; they are, however, oc- 

 casionally seen in shoals of different kinds together, 

 and make their migration, in large companies, from one 

 ocean to another. 



Although these animals, to a certain extent, are gre- 

 garious, yet, generally speaking, the common whales 

 are solitary, travelling in pairs, male and female, unless 

 they are attracted to a particular spot, either by an 

 abundance of choice palatable food, or a good situation 

 of the ice ; and then they are not unfrequently found in 

 great numbers together. 



There is an interesting fact connected with the food 

 of this species of the whale genus. They are, as already 

 stated, inhabitants of the olive-green waters of the 

 Greenland Seas, on account of the incalculable number 

 of the medusa and animalcule, which occupy a fourth 

 part of that ocean, or about twenty thousand square 

 miles. These whales, from the structure of the oeso- 

 phagus or gullet, which is so small as not to admit even 

 a small herring, are unable to derive any other subsist- 

 ence from the larger inhabitants of these seas. A pre- 

 paration of a portion of the oesophagus or gullet of a 

 whale is preserved in the Museum of the Royal College 

 of Surgeons, in London. 



