LOCAL AND SPECIFIC VARIETIES 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 the united labours of a flock of 

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

 forth and educate a common family.' Mr. Richard 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 who would try to 

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

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

 common with the parasitic genera of Cuculiclcc." 



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, when they do so for the protection of their young. 

 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 

 elites tin' water: Mr. Gould informs me that he believes they 

 are perfectly terrestrial, and 1 am told that at the Zoological 

 Gardens these birds and the Sandwich Islands Goose seem 

 cpuite awkward in the water." The MS also points out that 

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

 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 witli wondrous skill; yet its four toes are all 

 united by a web; the web, h#rever, is considerably hollowed 

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



" On tin- other hand, there 'Iocs nut exist a more thoroughly 

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

 I... nl. nil by membrane. The water-hen may lie 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, Pasaa, 

 &c, can swim well, ami yet have scarcely any traces of Web; 



