240 The Naturalist in La Plata. 



like shafts destitute of webs. This tail appears to 

 be purely ornamental. 



This extreme variety in structure indicates a 

 corresponding diversity in habits ; and, assuming it 

 to be a true doctrine that habits vary first and 

 structure afterwards, anyone might infer from a 

 study of their forms alone that these birds possess 

 a singular plasticity, or tendency to vary, in their 

 habits or, in other words, that they are exception- 

 ally intelligent ; and that such a conclusion would 

 be right I believe a study of their habits will serve 

 to show. 



The same species is often found to differ in its 

 manner of life in different localities. Some species 

 of Xenops and Magarornis, like woodpeckers, climb 

 vertically on tree-trunks in search of insect prey, 

 but also, like tits, explore the smaller twigs and 

 foliage at the extremity of the branches ; so that the 

 whole tree, from its root to its topmost foliage, is 

 hunted over by them. The Sclerurus, although an 

 inhabitant of the darkest forest, and provided with 

 sharply-curved claws, never seeks its food on trees, 

 but exclusively on the ground, among the decaying 

 fallen leaves ; but, strangely enough, when alarmed 

 it flies to the trunk of the nearest tree, to which it 

 clings in a vertical position, and, remaining silent 

 and motionless, escapes observation by means of 

 its dark protective colour. The Drymornis, a large 

 bird, with feet and tail like a woodpecker, climbs on 

 tree-trunks to seek its food; but also possesses 

 the widely-different habit of resorting to the open 

 plain, especially after a shower, to feed on Iarva3 and 

 earthworms, extracting them from a depth of three 



