28 Transactions. — Miscellaneous. 



flocks, and, in any case, with the young bird it is " follow niy 

 leader." The same remark may be made concerning the 

 migratory habits of the Norwegian lemming, the salmon, and 

 other animals. The periodical shifting of their places of abode 

 by certain animals may be regarded as racial habits, in which 

 the offspring are trained by their parents or seniors ; and it is 

 no more necessary to assume the existence of a special faculty 

 to account for the habit than it would be to assume the 

 existence of a special faculty in mankind to account for the 

 custom of some human families to shift periodically from the 

 town to the country. 



The nest-building habits of birds may be similarly ex- 

 plained, and even such extraordinary habits as that of the 

 Australian Megapodidae, w4iich build up immense mounds of 

 vegetable and other matter and deposit their eggs in the 

 middle, leaving them to be hatched by the heat evolved from 

 the fermentation of the decaying mass. One member of this 

 family — the Leipoa ocellata — forms a pile as much as 45ft. in 

 circumference and 4ft. in height of leaves thickly covered 

 with sand. It is assumed that these birds construct the 

 mounds without teaching or knowledge acquired by observa- 

 tion ; but I see no warrant for such a belief. How the racial 

 habit was originally acquired is a fair subject for research ; 

 but, having once been acquired, and the propensity incorporated 

 (so to speak) in the bird's mental system, it is easy to com- 

 prehend how the young megapod may acquire the art of build- 

 ing a mound, either from direct observation or from seeing 

 other birds perform the work. 



The beaver's remarkable habits of constructing dams and 

 water-canals, which, if constructed by human beings, would 

 be deemed proofs of considerable engineering skill, illustrate 

 my proposition. The beavers dwell together in families in 

 artificial habitations called "lodges," which are tenanted 

 by generation after generation. Some of the works con- 

 structed by the beaver, too, are of great antiquity, and there 

 is an instance upon record of a beaver-dam which appeared, 

 upon investigation, to be about a thousand years old, and was 

 still in use. The young beaver remains in the parental lodge 

 until the summer of its third year, when it starts housekeep- 

 ing for itself ; so that it has ample opportunity during its 

 residence in the parental domicile for receiving instruction 

 from its elders in the peculiar ways of beaverdom ; and when 

 it does begin life upon its own account it still enjoys oppor- 

 tunities of acquiring engineering skill by observing the labours 

 of other beavers, and from its own experience. Probably its 

 earlier works are less perfect than those whicli it executes 

 when it grows older, just as the nests made by young birds 

 are seldom as perfect as those made by older ones. 



