The Chief Morphological Features. 



While there have been some attempts to work out the mor- 

 phology of the Cicadellidse, yet it does not seem that the subject 

 has yet received much thorough investigation. Therefore in 

 this paper we propose to give only as much information on the 

 morphology as will enable one to recognize members of the 

 family, and enable them to use the keys for their specific de- 

 termination. It is hoped at some future time to carefully study 

 the morphology, both external and internal, of the family. 



As in all insects, the body of the leaf hopper is divided into 

 three distinct regions, namely, head, thorax, and abdomen. 

 The chief features of each are briefly described below and il- 

 lustrated in the accompanying plate (plate I). 



The upper or dorsal portion of the head is called the vertex. 

 There is no distinct division between this portion and the rest 

 of the head, but often there is more or less of a distinct margin 

 between it and the face. The greater portion of the latter is 

 called the front. It is not separated from the vertex by a dis- 

 tinct dividing line or suture, but is distinctly bounded laterally 

 by sutures which frequently run past the antennae clear to the 

 anterior margin of the head. On the lower side or ventrally 

 the front is bounded by a transverse suture. The clypeus is 

 the rectangular sclerite attached to the anterior or lower edge 

 of the front. The lorse are the rather semicircular sclerites on 

 either side of the front and clypeus, while the genw are the 

 large sclerites extending from below the eyes and surrounding 

 the lorw. It might be stated that Cogan claims that the clypeus 

 proper is not clearly differentiated in the Homoptera, and that 

 what is usually called the clypeus is really the labrum or upper 

 lip. 



The eyes are of two kinds, compound and simple. The 

 former are always large and prominent and occupy a large part 

 of the head. The simple eyes or ocelli are always small, and 

 are lacking in many members of the Typhlocybini. In the 

 Paropinse and Bythoscopinse they are situated on the front, be- 

 low the margin of the vertex, in the Cicadellinse and Gyponinse 



(40) 



