In spite of the voluminous literature of “animal mimicry” since Bates first published his classical memoir on the subject, the exact nature of the process whereby insects and other creatures “mimic” (though that is not the appropriate word) the appearance of other species is still far from being understood. All we know is that this power, this resemblance of a beetle or a butterfly to the ground upon which it sits, the sticks among which it creeps, or the leaves among which it flutters, helps to save it from destruction, while it is a decided advantage to it to “mimic” another insect which is sedulously avoided by birds. The observations in this byway of zoology are as curious as any yet made. It is found, for instance, that an American spider (Cyrlarachne) takes the semblance of a little land shell very abundant in the localities which it frequents; and that another species (Thomisus alcatorius), remarkable for the length of its forelegs, so fastens itself on the stems of grasses as to be nearly indistinguishable from the spikelets. Some observations, for which we are indebted to M. Heckel of Marseilles, throw a good deal of light on the origin of mimicry, at least so far as the assumption of protective coloration is concerned. There is a spider (Thomisus onustus) very common in the south of France which conceals itself in the flower of a species of wild convolvulus for the purpose of trapping two kinds of fly on which it feeds. This convolvulus is found in three principal varieties: white, pink with deeper spots of the same hue, and light pink forms with a slight greenishness on the external wall of the flower. Each of these three varieties is visited by the spider. But the varieties of spider conform in hue to the varieties of the flower, and each confines itself to the one which is most protective to it. If, however, the animal is confined to a Dahlia versicolor, it conforms to the hue of its new abode--that is, the pink one turns to red, and, in like manner, if transferred to the yellow snapdragon, it takes the color of this flower. They change in shade as the shade of their host changes, and when pink, white, green, and yellow varieties are confined together in a box they all become nearly white.