Mr.

Bates may almost be said to have actually witnessed the process by which the mimickers have come so closely to resemble the mimicked; for he found that some of the forms of Leptalis which mimic so many other butterflies, varied in an extreme degree.

In one district several varieties occurred, and of these one alone resembled, to a certain extent, the common Ithomia of the same district.

In another district there were two or three varieties, one of which was much commoner than the others, and this closely mocked another form of Ithomia.

From facts of this nature, Mr.