LOCAL AND SPECIFIC VAEIETIES OF INSTINCT. 253 



of the screech-owls {Strix, as now limited). In the ani 

 {Crotophaga) , which have much in common with the coucals 

 of the major continent, while in other respects their habits 

 are very peculiar for birds of this family, ' an immense nest 

 of basket-work ' is formed by tlie united labours of a flock of 

 them, usually on a high tree, where 'many parents bring 

 forth and educate a common family.' Mr. Kichard Hill, 

 whose statements in Jamaican ornithology are worthy of 

 unlimited confidence, writes Mr. Gosse, observes : ' Some 

 half-dozen of them together build but one nest, which is large 

 and capacious enough for them to resort to in common, and 

 to rear their young ones together.' All of these diversified 

 facts must be borne in mind by naturalists wdio would try to 

 assign a reason for the parasitic habits of various Cucididce, as 

 also those of the ' cow-buntings,' which have no other trait in 

 common w4th the parasitic genera of Cuculidce." 



The Upland Goose of South America furnishes an admir- 

 able case of a fixed specific variation of instinct. These birds 

 are true geese with well webbed feet ; yet they never enter 

 the water except perhaps for a short time after hatching their 

 eggs, w^hen they do so for the protection of their youno-. 

 Similarly, Mr. Darwin's MS says of the Upland Geese of 

 Australia, which also have well webbed feet, that '' they are 

 long-legged, run like gallinaceous birds, and seldom or never 

 enter the water : Mr. Gould informs me that he believes they 

 are perfectly terrestrial, and I am told that at the Zoological 

 Gardens these birds and the Sandwich Islands Goose seem 

 quite awkward in the water." The MS also points out thati 

 "the long-legged Flamingo likewise has webbed feet, yeti 

 lives on marshes, and is said seldom even to wade except in 

 very shallow water. The Frigate bird with its extremely 

 short legs never alights on the water, but picks up its prey 

 from the surface with wondrous skill ; yet its four toes are all 

 united by a web ; the web, however, is considerably hollowed 

 out between the toes, and so tends to be rudimentary. 



" On the other hand, there does not exist a more thoroughly 

 aquatic bird than the Grebe, but its toes are only widely 

 bordered by membrane. The water-hen may be constantly 

 seen swimming about and diving with perfect ease ; yet its 

 long toes are bordered by the merest fringe of membrane. 

 Other closely allied birds belonging to the genera Crex, Fassa, 

 &c., can swim well, and yet have scarcely any traces of web ; 



