The curious series of cells shown in the left-hand figure is made by a hymenopterous insect belonging to the genus Icaria, and the specimens from which the drawing was taken may be seen in the British Museum. They are made of a paper-like substance, much resembling in look the material of which the common wasp builds its cells, but as they are exposed to the air, they are necessarily tougher and stronger than ordinary wasp cells, which are shielded from the elements. The insects belonging to this genus make nests of very diverse forms, some of which are stuck on leaves in a most curious manner, reminding the observer of the parasitic mollercoids that cover the stems and fronds of large seaweeds. Others, however, are not dependent upon leaves for their support, but stand out boldly from the branches to which they are fixed, supported entirely by a footstalk composed of the same material as the cells, though necessarily of a harder and more compact substance. [Illustration] As many of these nests have been found in India, it is easy to trace the manner in which they were made. The mother insect began by kneading woody fibre into a paste, and making the footstalk of the future nest. One end of this footstalk is attached very strongly to the branch, and to the other end is fastened the first cell. As soon as the Icaria has made the first beginning of the cell, and raised--or rather lowered--the walls to a fourth or so of their complete dimensions, she inserts an egg into the yet imperfect cell, and adds to the walls while the egg is being hatched. Her next duty is, to add a second cell, and this is quickly followed by a third, all these cells being fastened to each other on three or four of their sides, leaving the others free and unattached. It is evident that by this mode of construction the cells nearest the branch must be the longest, because they are begun the soonest, and this will always be found to be the case. Now, there is a point respecting which the attention of the reader must be specially solicited. On looking at the cells, he will see that they are partly cylindrical and partly angular, and may perhaps think that this fact goes towards proving that the hexagonal shape of bee cells is owing to mutual pressure, the outer sides of the cells being rounded, while the inner are angular. But, there are other cells in existence, built by allied insects, and formed in an analogous manner, and which are either angular or cylindrical, exactly according to the instinctive powers of the insect which built them.