The present Order of insects, although of very limited extent, contains several important species, of which the noisy Cicadas, destructive Aphides, and numerous Bugs, and Lice, can be cited as familiar examples. The Hemiptera may be conveniently divided into the two following groups:-- The _Homoptera_, comprising all the species in which the anterior wings are entirely membranous, and-- The _Heteroptera_, including those having the basal portion of the anterior wings thickened, and quite opaque. These peculiarities have induced some entomologists, who regard the structure of the wings of the greatest importance in classifying, to arrange the insects included in the Homoptera and Heteroptera, into two distinct Orders; but their uniform character in all other respects renders this, I think, hardly desirable. Group HOMOPTERA. Family CICADIDÆ. _Cicada cingulata_[22] (Plate XX., fig. 1, 1a pupa). This beautiful insect may be found in great numbers {119}amongst brushwood during the hot sunny days so common from January till March. Its larva inhabits the earth earlier in the summer, and its curious pupa can often be observed crawling up the stems of trees in order to allow the perfect insect to emerge. After this has taken place the exuviæ still remain firmly attached to the tree, and are very conspicuous objects; but if it is desired to remove them great care must be taken not to break off the legs, which are always very brittle. The perfect insects are at once betrayed by their loud singing, which, in certain localities, becomes quite deafening. This noise is entirely confined to the males, and proceeds from two large drum-like organs, situated on the under surface of the abdomen near its base, which, in conjunction with the curious ovipositor existing in the females constitute good sexual distinctions throughout the family. The structure of these two organs having been admirably described by several European authors renders it quite unnecessary for me to do so here. Closely allied to the present insect is _Cicada muta_, the female of which is depicted on Plate XX., fig. 2. The male is often of a reddish-brown colour, but the insect is an extremely variable one. It is found in similar situations to _C. cingulata_, but appears rather earlier in the year. Family CICADIDÆ. _Cicada iolanthe_, n.s. (Plate XX., fig. 3, 3a larva, 3b pupa).