nest operations of keeping these masses moist enough for the nurture of the larvæ. The material of these pots although called wax is not properly so, but is an agglutination of collected vegetable matter, for it is not plastic to the fingers like wax, and it burns, leaving a carbonaceous residuum very attractive to moisture. The larvæ hatched from the eggs now deposited produce the first neuters, which spin a cocoon wherein they rapidly undergo their transformations. They are, in the first instance, aided to emerge from their silken cot by the parent gnawing off its top, but subsequently this duty is performed, as the family increases, by the neuters then developed. The young bee, on emerging from its cocoon, is not thoroughly hardened in its integument, and its pubescence also acquires by degrees only its proper colouring; all this is not long in being effected, but, until they are thoroughly able to fly forth, they continue to be fed by their elder sisterhood, for the neuters are properly abortive females. Males, and further productive females are produced later in the spring, and are smaller than the normal sizes of those sexes; the autumnal brood, consisting also of males and females, again resume the full size of the complete insect, and it is these females which, after impregnation, hibernate and reappear in the following early spring to be each the parent of a new progeny. The population of these nests varies considerably in the several species: in some, as in that of _Bombus terrestris_, there are more than two hundred, and in that of _B. senilis_ there are about a hundred and forty; but it is in those that construct their nests above the ground that the fewest are found. As with the general population, so with the relative proportions of the sexes, the several species vary. Of course all these numbers are approximative only, as under certain conditions they will necessarily differ, nor are the general or relative numbers identical, even in the same species, in the same season, and in the same locality. The proportions are usually somewhat like this, about double the number of neuters to females, and nearly the same number of males as of females. In some of the communities there are even as few as twenty neuters, and these, of course, comprise those species which are most rarely found by collectors. The most pugnacious of all, and the fiercest in their attacks and most painful in their stings, are those which live underground or in cavities formed of accumulations of stones, and it is these which are the least constructive in their habitations, as if their truculent nature rejected the concomitants of incipient civilization; for it is those which build moss-nests, requiring a certain amount of skill, that are the most gentle in their habits. With the increase of numbers in the habitation, the rapidity of the labours progresses, and the accumulations quickly increase; but there is always