362 STRANGE DWELLINGS. 



about one-third in proportion to the actual object. Several of 

 these singular nests are in the collection at the British Museum. 

 Occupying the lower part of the illustration is seen a leaf 

 upon which are piled a number of fragments of leaves, so as to 

 form a rudely conical heap. This is also the work of a spider, 

 and is made with even more ingenuity than the two preceding 

 specimens. In the first instance, the spider has spun a hollow 

 case of silk, similar in principle of construction, though not in 

 form, to the spherical t.gg cases made by several British spiders. 

 In the second instance, the creature has chosen a number of 

 concave seed-pods, and, by adjusting their edges together and 

 fastening them with silk, made a hollow nest, which only 

 requires to be lined in order to make it a fit nursery for the 

 young. But, in the present example, the work of nest-making 

 has been much more elaborate, for the structure has been re- 

 gularly built up of a great number of pieces, each being arranged 

 methodically upon the other, very much as children in the 

 streets build their oyster-shell grottoes. The labour hiust have 

 been considerable, even if the spider had nothing to do but to 

 arrange and fasten together pieces of leaves which had already 

 been selected. 



In the accompanying illustration three most remarkable nests 

 are given, all of them the work of hymenopterous insects, and 

 all serving in some degree to illustrate the hexagonal system of 

 cell-building, so common among the hymenoptera. 



Of these, perhaps, the central figure is the most interesting, 

 because it entirely sets at rest a question which is periodically 

 agitated. It is made by an insect belonging to the genus Icaria. 

 Perhaps my readers may remember that on a former page 

 the celebrated bee-cell problem is described, and that mention 

 is made of the many theories which have been invented to 

 solve the riddle. Among them the two most conspicuous are 

 those which are known as the equal pressure theory and the 

 excavation theory. Differing as they do in many respects — one 

 attempting to prove that each cell is forced into the hexagonal 

 shape by the pressure of six cells surrounding it, and the other 



