94 THE ZOOLOGIST. 



In the Sperm-Whale the massive teeth, which some (with a 

 tinge of romance) say the animal uses as lures for the cuttle- 

 fishes on which it feeds, have no enamel, only dentine covered 

 with cement, and they form good ivory. In the allied Ziphius, 

 again, only one tooth occurs on each side near the anterior end 

 of the mandible. In Mesoplodon these form strong tusks (one 

 on each side), larger in the male than in the female — indeed, it 

 has more than once happened that this form has been described 

 as edentulous, since they are sometimes hidden in the gum, or 

 may have been lost. In the Bottle-nose [Hyperoodon) they are 

 minute and entirely concealed in the gum, so that the animal is 

 practically toothless.* In the Susu they are numerous, sharp in 

 the young, worn in the old. Amongst the Dolphins the teeth, 

 as a rule, are more or less numerous in both jaws. In the 

 Narwhal, however, besides some irregular rudiments, only a 

 pair occur in the upper jaw-bones (maxillaries). These are 

 concealed in the female, but in the male the left tusk is more 

 than half the length of the animal, with a sinistral spire. f The 

 teeth of the Killer are powerful organs for prehension — sharp 

 in the young, blunt and sometimes angled from friction in the 

 old animals. The crowns are coated with enamel. 



The stomach in the Toothed Whales is complex, some authors 

 attributing no fewer than six or seven chambers to that of the 

 Bottle-nose. Others, again, are of opinion that only two com- 

 partments exist in the stomach of the Pilot-Whale, but, as 

 Dr. Murie, in his able memoir, states, there are at least four. 

 The first cavity in this species (Pilot-Whale) is the largest — and 

 this in the Porpoise is characterized by its pale, tough, non- 

 vascular lobulated folds ; the second a globular sac, with highly 

 vascular ridges in the Porpoise ; the third also rounded ; while 

 the fourth is an elongated cavity with the pylorus at the end of 

 it. There is thus a certain resemblance to the condition in the 

 Sirenians and in the ruminant ungulates, such as the ox and 

 sheep. 



It is an interesting fact that these huge inhabitants of the 



'^- As in the examples in many museums. 



f Some suppose it pierces the ice with its tusk to breathe ; others that it 

 uses it as a spear for fishes. Occasionally two tusks of nearly equal length 

 are present. 



