able that crouching in a bird should have come before flying than after it, or, at least, that it should have been resorted to by certain species, on account of their flight having become weak. It is conceivable that some birds may have alternately lost and reacquired the power of flight many times in their genealogical history. But where have the majority of the young gulls gone? That they have left the island seems evident, for, were it otherwise, they would either be all about the heather, or fill the air more numerously than do the mature birds, when they cluster above me in my walks. In the air, however, none are to be seen, though, as by far the greater number must now be full-fledged, it is there that they ought to be, with the rest. On the ground there are, as I say, a few that seem to have been later hatched, and are not yet matriculated in flight. Their proportion, however, is not more than one to a hundred of the grown gulls, whereas since every pair of these rears three young, it should be as three to two. Gilbert White speaks of that general law in accordance with which young birds are driven away by their parents, when they are no longer dependent upon the latter's attention, but can feed and look after themselves; but with social birds this law of expulsion is apt to merge in a larger one, that, namely, which is expressed in the old adage that "birds of a feather flock together." We often see this illustrated in the case of the sexes, and after watching kittiwakes at the close of the breeding-season, I can have no
