NESTS OF APOICA. 601 



fail to express their surprise at so curious a structure, and their 

 admiration of the manner in which these natural homes are con- 

 structed. 



In a recent portion of this work the hexagonal principle of con- 

 struction has been mentioned as applied to separate cells of cer- 

 tain hymenoptera, and that no explanation has been given of the 

 mode by which the six-sided cells are made. It is always easier 

 to explode previous theories than to supplant them with one that 

 really explains the enigma, and such is certainly the case with 

 these cells. But when we come to examine the group of nests 

 which are made by an insect called Apoica pallida, the subject 

 takes a wider range, and we are even more hopelessly bewildered 

 than before. In the nests already mentioned the cells are hexag- 

 onal, but in these specimens the entire nests assume a form more 

 or less hexagonal, as may be seen by reference to the illustration. 



In order to prevent misunderstanding, I must here remark, that 

 the seven nests or cell groups were not all found adhering to a 

 single branch, as seems to be the case, but that they have been 

 placed near each other in such a manner as to allow of easy com- 

 parison, and to show their peculiar form. The large mushroom- 

 shaped nest in the centre, and the small cell group which occu- 

 pies the extremity of the bough, appear as they were formed by 

 the insects, but the others have only been arranged for the con- 

 venience of comparison. 



Even their position has been necessarily altered. Nests of this 

 kind are always placed with the mouths of the cells downward ; 

 but, as their peculiar form could not easily be seen if they were 

 allowed to retain their natural position, some of them have been 

 set on their edges, so as to exhibit their outline to the spectator. 

 This is notably the case with that nest which occupies the left 

 hand of the illustration, and which is the most striking of all the 

 specimens. 



If the reader will refer to the illustration, he will see that the 

 nests are by no means uniform in size or shape. The larger one, 

 for example, which occupies the centre, rather exceeds ten inches 

 in diameter, while the small nest at the end of the same branch is 

 scarcely half as wide, and the others are of all the intermediate 

 sizes. In shape, too, they differ, some being perfectly hexagonal, 

 others partly so, while others, again, are nearly circular, though 

 on a careful inspection they show faint traces of the hexagonal 

 form. 



