Certainly the water-thrushes (Seiurus ludovicianus, S.auricapillus, and S.noveboracensis) have taken many preliminary steps to becoming as aquatic as the dipper; and the winter-wren, and even the Maryland yellow-throat are not far behind."[40] Another curious example of the way in which species have been modified to occupy new places in nature, is afforded by the various animals which inhabit the water-vessels formed by the leaves of many epiphytal species of Bromelia.

Fritz Mueller has described a caddis-fly larva which lives among these leaves, and which has been modified in the pupa state in accordance with its surroundings.

The pupae of caddis-flies inhabiting streams have fringes of hair on the tarsi to enable them to reach the surface on leaving their cases.

But in the species inhabiting bromelia leaves there is no need for swimming, and accordingly we find the tarsi entirely bare.

In the same plants are found curious little Entomostraca, very abundant there but found nowhere else.