The genus Goniodes (Fig. 125, G. stylifer, the turkey louse) is of great interest from a morphological and developmental point of view, as the antennae are described and figured by Denny as being "in the males cheliform (Fig. 126, _a_, male; _b_, female); the first joint being very large and thick, the third considerably smaller, recurved towards the first, and forming a claw, the fourth and fifth very small, arising from the back of the third." He farther remarks, that "the males of this [which lives on the turkey] and all the other species of Goniodes, use the first and third joints of the antennae with great facility, acting the part of a finger and thumb." The antennae of the females are of the ordinary form. This hand-like structure, is, so far as we know, without a parallel among insects, the antennae of the Hemiptera being almost uniformly filiform, and from two to nine-jointed. The design of this structure is probably to enable the male to grasp its consort and also perhaps to cling to the feathers, and thus give it a superiority over the weaker sex in its advances towards courtship. Why is this advantage possessed by the males of this genus alone? The world of insects, and of animals generally abounds in such instances, though existing in other organs, and the developmentist dimly perceives in such departures from a normal type of structure, the origin of new generic forms, whether due at first to a seemingly accidental variation, or, as in this instance, perhaps, to long use as prehensile organs through successive generations of lice having the antennae slightly diverging from the typical condition, until the present form has been developed. Another generation of naturalists will perhaps unanimously agree that the Creator has thus worked through secondary laws, which many of the naturalists of the present day are endeavoring, in a truly scientific and honest spirit of inquiry, to discover. [Illustration: 124. Louse of the Goat.] [Illustration: 123. Louse of the Cat.] In their claw or leg-like form these male antennae also repeat in the head, the general form of the legs, whose prehensile and grasping functions they assume. We have seen above that the appendages of the head and thorax are alike in the embryo, and the present case is an interesting example of the unity of type of the jointed appendages of insects, and articulates generally. [Illustration: 120. Antennae of Goniodes.]