Most of our best authorities are now convinced that the various larval and pupal stages of insects have thus been acquired through adaptation, and not through inheritance from some ancient form.

The curious case of Sitaris--a beetle which passes through certain unusual stages of development--will illustrate how this might occur.

The first larval form is described by M.

Fabre, as an active, minute insect, furnished with six legs, two long antennae, and four eyes.