130 TEXT-BOOK OF ZOOLOGY 



the large size of the head (quarter to one-third the entire length of the 

 body), and more especially the extraordinary length of the jaws. 



(d) The shovel-like shape of the lower jaw is correlated with the 

 flattened shape of the body. 



(e) Whilst in all other mammals the food passes above the larynx 

 (which on that account is provided with a lid), in the whale it passes 

 around it, the larynx being firmly wedged into the lower nasal aperture 

 (in the throat). This arrangement enables the whale to breathe and 

 swalloiv food simultaneously. 



(/) Salivary glands are absent, the food itself being extremely slimy. 

 (See p. 8.) 



8. The Whale and its Offspring. — (a) Being obliged, from the moment 

 of their birth, to follow their mother in the water, the young are brought 

 into the world in a high state of development, and perfectly capable of 

 •motion. (Contrast the young of the cat and kangaroo.) 



(b) The teats of the female lie within deep pouches on the abdomen. 

 The young inserts the front part of its head into these, and grasps the 

 teat with its lips. The lips, however, are but slightly mobile, and useless 

 for sucking, for which reason the mother injects the milk by jerks into 

 the mouth of the young, whereby it is prevented from mingling with the 

 water. 



C. Related Species. 



In the same group as the Greenland whales (Whalebone whales, Mysti- 

 cetce) are the so-called "finner whales," which also inhabit the Northern 

 seas, and take their name from the possession of a dorsal fin. The largest 

 of this family, and, indeed, the largest existing animal, is the Rorqual 

 (Balcenoptera sibbaldi) , measuring about 100 feet. Opposed to the Bal senidae 

 or Toothless whales, wehave the division of the Toothed whales (Denticetce) 

 the mouth of which is furnished with many pointed conical teeth of equal 

 length. (See seal.) This oral armature, and the nimbleness and rapidity 

 which distinguish all their movements, in themselves indicate sufficiently 

 that we are here dealing with true carnivorous animals. Their food 

 consists principally of fish, molluscs and crustaceans. One of them, the 

 Grampus or Killer {Orca gladiator), goes specially in pursuit of seals and 

 other whales, and when assembled in shoals will even attack the gigantic 

 Greenland whale, tearing the flesh from its body piecemeal. The most 

 familiar species of the North Sea and Baltic is the Porpoise {Phocmia 

 communis), which belongs to the dolphin family. It only reaches a 

 length of about 7 feet. Though its playful antics provide much enter- 

 tainment to passengers on ships, it is much detested by sea-fishermen 

 for plundering and tearing their nets. Another extraordinary member 



