pseudo-pupae and continuing the series of changes in June of the following year; at that time the pseudo-pupa returns to a larval form (12 of the fig. cited), differing comparatively little from the second instar. The skin, though detached, is again not shed, so that this ultimate larva is enclosed in two {274}dead skins; in this curious envelope it turns round, and in a couple of days, having thus reversed its position, becomes lethargic and changes to the true pupa, and in about a month subsequent to this appears as a perfect Insect, at about the same time of the year as it would have done had only one year, instead of two, been occupied by its metamorphosis. M. Fabre employs the term, third larva, for the instar designated by Riley Scolytoid larva, but this is clearly an inconvenient mode of naming the instar. _Sitaris humeralis_ is now very rare in Britain, but it seems formerly to have been more common, and it is not improbable that its triungulin may have been the "_Pediculus melittae_," that was believed by Kirby to be a sort of bee-louse. Some species of the genus _Meloe_ are still common in Britain, and the Insects may be seen with heavy distended abdomen grazing on herbage in the spring. The females are enormously prolific, a single one producing, it is believed, about 10,000 eggs. _Meloe_ is also dependent on _Anthophora_, and its life-history seems on the whole to be similar to that of _Sitaris_; the eggs are, however, not necessarily deposited in the neighbourhood of the bees' nests, and the triungulins distribute themselves on all sorts of unsuitable Insects, so that it is possible that not more than one in a thousand succeeds in getting access to the _Anthophora_ nest. It would be supposed that it would be a much better course for these bee-frequenting triungulins to act like those of _Epicauta_, and hunt for the prey they are to live on; but it must be remembered that they cannot live on honey; the one tiny egg is their object, and this apparently can only be reached by the method indicated by Fabre. The history of these Insects certainly forms a most remarkably instructive chapter in the department of animal instinct, and it is a matter for surprise that it should not yet have attracted the attention of comparative psychologists. The series of actions, to be performed once and once only in a lifetime by an uninstructed, inexperienced atom, is such that we should _a priori_ have denounced it as an impossible means of existence, were it not shown that it is constantly successful. It is no wonder that the female _Meloe_ produces 5000 times more eggs than are necessary to continue the species without diminution in the number of its individuals, for the first and most important act in the complex series of this life-history is accomplished by an extremely indiscriminating instinct; the {275}newly hatched _Meloe_ has to get on to the body of the female of one species of bee; but it has no discrimination whatever of the