The composite eyes present nothing very peculiar in this order. In general they are rather of large size, and at times placed very prominently. In the genus Aleyrodes there appear to be a pair on each side. Stemmata exist in most of the genera, but in some no trace of them can be observed. They are of remarkable size in Reduvius, almost equalling the dimensions of composite eyes, and seem to be wanting in Naucoris, Notonecta, Nepa, and some other tribes. When two in number, (which is frequently the case among the Hemiptera,) they are sometimes placed rather behind the eyes, at other times on the crown of the head, (as in Cercopis, Ledra, &c.) and occasionally (as in the Fulgoridæ,) between the eyes and the antennæ. In the genus Jassus they present the singular anomaly of being placed under the head. Sometimes they are remote from each other, (Scutellera, Edessa, &c.) at other times with their edges almost touching (Reduvius, &c.) In shape also they offer some differences, the usual round form being exchanged, in Fulgora serrata, for an oblong with a longitudinal impression; in another example of the same genus, (Fulgora diadema,) the depression is circular. In the genus just named, the ocelli deviate in another respect from their ordinary appearance, being, instead of the usual black or hyaline colour, of a fine yellow in F. laternaria, and white in F. candelaria. In some kinds of Cicadæ they are red.
The antennæ vary greatly, as will appear from the descriptions afterwards given of them as aiding in distinguishing the different families. In the homop-
