HEMIPTERA. 265 



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 occa- 

 sionally (as in the Fulgoridae,) between the eyes and 

 the antennae. In the genus Jassus they present the 

 singular anomaly of being placed under the head. 

 Sometimes they are remote from each other, (Scu- 

 tellera, 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. cande- 

 laria. In some kinds of Cicadse they are red. 



The antennae vary greatly, as will appear from the 

 descriptions afterwards given of them as aiding in 

 distinguishing the different families. In the homop^ 



