INTRODUCTORY. 5 



abstained from including such detail as is given else- 

 where at far greater length than I could spare in these 

 pages. 



Coming for a moment to the zoological divisions, which 



are of considerably greater interest and importance, he 



task of establishing fixed rules whereby field- 



Zoologica naturalists learn to associate peculiar types of 



divisions. . i i 



animals with certain physical conditions opens 

 up a wealth of fascinating study, and still more fascinating, 

 because more daring, deduction. Let us take an example 

 in the birds and fishes found to frequent rocky or sandy 

 coasts. In either class we find well-marked distinctions. 

 Thus, the ornithologist knows that he will find on a bold 

 rocky coast, like, say, that of Cornwall, such fowl as 

 puffins, guillemots, cormorants, and gannets, birds that 

 find their food in deep water, the majority by diving; 

 whereas on the low sandy shore of Essex, on the other 

 hand, he will look for long-legged wading dotterels and 

 sandpipers, all of which seek their molluscan and insect 

 food in the shallows. Nor is the contrast in the legs of 

 the birds in these two groups more striking than that 

 afforded by their bills, the waders being armed with long 

 slender bills that they can thrust into the mud, the divers 

 having short stout bills, usually hooked, to assist in the 

 capture of the slippery fish on which they feed. In like 

 manner, the student of fish knows well enough that along 

 with the puffins and their kind he will find conger, pollack, 

 and wrasse ; with the waders, flat fish and whiting. 



These principles admit of almost infinite extension, and 

 if an occasional exception to the rule should be sprung 

 upon the investigator and it must be confessed that 

 Nature holds some strange surprises in store for those who 

 are so bold as to pry into her secrets he will, after the 

 first shock has worn off, cheerfully accept it as. the one 

 thing necessary to prove the rule he has laboured so hard 

 to establish. 



Thus, he will look for certain types in each district, the 



