THE BRITISH MAMMALS : ORDERS, FAMILIES, ETC. 15 



3. (Delphinidas) 



Teeth, three to seven pairs in front of lower jaw 

 Grampus, 68. 



Teeth in both jaws. 



Beak absent or inconspicuous. 



Mottled grey above and below ; long tusk in the 



male Monoceros, 63. 



White above and below Delphinapterus, 64. 

 Black above and below, with white throat patch 



and occasionally a narrow abdominal stripe 



Globicephalus, 67. 



Black above, white below. 

 White spot over eye ; dorsal tall ; twelve pairs 



of large conical teeth Orca, 66. 

 No white spot over eye ; dorsal low ; sixteen to 



twenty-six pairs of small spatulate teeth 



Phocana, 65. 



Beak short. 



Length of mouth not exceeding height of dorsal 

 fin Lagenorhynchus, 69, 70. 



Beak rather long. 



Length of mouth exceeding height of dorsal fin. 

 Beak tapering ; palate not grooved ; teeth 

 twenty-one to twenty-five pairs ; lower jaw 

 longer than upper Tursiops, 72. 

 Beak elongated ; palate grooved ; teeth forty to 

 sixty pairs; jaws equal in length Delphintts, 



By the aid of these keys, mere skeleton keys as some of them are, 

 we can find the genus of any British mammal ; but to make 

 assurance further sure, and for other good reasons, we can with 

 advantage be a little more technical. It will never do to close this 

 chapter without a few words on the mammalian orders and families, 

 though the scope of our work forbids our doing more than touch on 

 salient differences easily recognisable or useful in identification. 



We have been dealing with bats and shrews, cats and foxes, 

 stoats and seals, mice and rabbits, deer and whales what 

 characteristics have they in common that they should be grouped 

 together ? In short, what are mammals ? Mammals are crinigerous 

 vertebrates, even the whales having hairs at some period of life, 

 though with most of them it is only at an early stage. They are 

 warm-blooded, and breathe by lungs ; and they nourish their young 

 with milk secreted in cutaneous glands placed in pairs on the 

 ventral surface. The head is as a rule joined to the body by a neck 

 in which there are, with few exceptions, seven vertebrae and the 

 backbone is usually prolonged into a tail. The limbs are normally 

 four in number, terminating in claws, nails, or hoofs, but in some cases 



