The usual dimensions of the nest are one and a half inches long by three-quarters of an inch wide, or a trifle larger.

The colour is a pale tan, like that of a grain of wheat.

Brought in contact with a flame the nest burns readily, and emits an odour like that of burning silk.

The material of the nest is in fact a substance similar to silk, but instead of being drawn into a thread it is allowed to harden while a mass of spongy foam.

If the nest is fixed on a branch the base creeps round it, envelops the neighbouring twigs, and assumes a variable shape according to the accidents of support; if it is fixed on a flat surface the under side, which is always moulded by the support, is itself flat.