Crass I]. GREEN WOODPECKER. 
they are provided with a long flender tongue, 
armed with a fharp bony end barbed on each 
fide, which by the means of a curious apparatus of 
mufcles* they can exert at pleafure, darting it to 
a ereat length into the clifts of the bark, transfix- - 
ing and drawing out the infects that lurk there. 
They make their nefts in the hollows of trees: in 
order therefore to force their way to thofe cavities, 
their bills are formed ftrong, very hard, and 
wedge-like at the end; Dr. Derham obferves, that 
a neat ridge runs along the top, as if an artift had 
defigned it for ftrength and beauty. Yet it has 
not power to penetrate a found tree: their per- 
foration of any tree is a warning to the owner to 
throw it down. 
Their legs are fhort, but ftrong; their thighs 
very mufcular: their toes difpofed, two backwards, 
two forward: the feathers of the tail are very ftiff, 
fharp pointed and bending downwards. The three 
firft circumftances do admirably concur to enable 
them to run up and down the fides of trees with 
ereat fecurity ; and the ftrength of the tail fupports 
them firmly when they continue long in one piace, 
either where they find plenty of food, or while they 
are forming an accefs to the interior part of the 
timber. This form of the tail makes their flight 
very awkward, as it inclines their body down, and 
forces them to Ay with fhort and frequent jerks 
* Phil. Tranf. Martin's abridg, V. p. 55. plate 2. 
when » 
Nest. 
