POLYBIA. 



443 



of several groups, and may therefore be placed in either of them. 

 For example, the South American wasp, which makes the nest 

 called popularly the " Dutchman's pipe," may be ranked either as 

 a builder, a pensile, or a social insect. In such cases, therefore, I 

 have endeavored to select that characteristic which seems to be 

 marked most strongly, and have arranged the insects accordingly. 

 Just as the hymenoptera are chief among the pensiles and the 

 builders, so are they chief among the Social Insects, and the spe- 

 cies which may be placed in this group are so numerous, that it 

 will only be possible to make a selection of a few, which seem 

 more interesting than the others. 



Polybia. 



In the British Museum there are some very remarkable nests 

 made by hymenopterous insects belonging to the genus Polybia, 

 several of which are drawn in the accompanying.illustration. As 



