246 Transactions. — Miscellaneous. 



is nothing to lead us to suppose that this is an isolated in- 

 stance. Indeed, many fresh-water fish are obviously modifi- 

 cations of marine forms. Heilprin writes, "Of so little 

 importance does a change of medium appear to be in many 

 cases that it is frequently very difiicult, or impossible, to indi- 

 cate whether a given group of fishes is more properly of a 

 marine or fresh-water type. The numerous instances where 

 certain species of a genus are of one habit and other species 

 of the same genus of the opposite habit render the determina- 

 tion of this question still more difficult." 



Some animals are of a more restless disposition than 

 others. We find such to be the case amongst domesticated 

 races. Some cows are habitual fence-breakers, and special 

 means have to be adopted to keep them in enclosed fields ; 

 while other cows, so long as a field contains sufficient pasture 

 for their wants, will remain contentedly in it. Even a dull- 

 witted creature like the domesticated sheep exhibits similar 

 idiosyncracies. I knew a farmer who owned a small flock of 

 sheep which was so addicted to straying that the sheep 

 actually learned to leap over gorse fences of considerable 

 height. Wild animals doubtless exhibit similar traits of cha- 

 racter ; and when, impelled by a desire for change, a herd of 

 animals moves on to a fresh region, the effect may be that it 

 will permanently take up its abode in a new country, where 

 its changed environment will cause it to ultimately develops 

 into a new species. Even if it leaves its original habitat 

 owing to lack of food or persecution by enemies, the intelli- 

 gence of the animal nevertheless comes into play by leading 

 it to migrate and choosing the direction. But for the exercise 

 of intelligence the animal would fail to seek food in fresh 

 regions or to retreat thither from its enemies ; and it is easy 

 to perceive that a particular herd of animals of quicker 

 intelligence than another herd might escape dangers which 

 would prove fatal to the latter. The extraordinarily large 

 herds of antelopes which, until recently, roamed in South 

 Africa could never have existed in a country so abounding in 

 savage beasts of prey but for the exercise of ceaseless vigilance 

 on the part of the members of those herds, and any particu- 

 lar herd which relaxed its vigilance must speedily have dis- 

 appeared. The alertness of the antelope's disposition finds 

 its outward expression in the physical structure of the animal; 

 a vigilant mind is aided by the power of rapid flight, while 

 the power of rapid flight would be of little use divorced from 

 an active intelligence. 



The circumstance that an animal of feeble frame is subject 

 to the frequent attacks of a beast of prey serves to keep the 

 intelligence of both up to the highest pitch ; to make the 

 assailant cautious and cunning, and the attacked vigilant and 



