LAWSON: KANSAS CICADELLID^. 41 



they are situated on the vertex, while in the Jassinse they are 

 on or near the margin of the vertex. 



The antennse or feelers are always setaceous or bristle-like. 

 They are on the face between the compound eyes and the front. 

 The basal segments are large but soon they become very small. 

 The number of segments is comparatively large. In the genus 

 Idiocerus the antennse are used in the differentiation of the 

 species due to the possession in the males of variously-shaped, 

 flattened discs at the apex. 



The mouth parts consist of a large 3-jointed beak or pro- 

 boscis which, in a groove on its anterior or dorsal surface, bears 

 a minute triangular sclerite and two pairs of brown stylets 

 which run its whole length. The former is claimed by Cogan 

 to be the small epipharynx. By some it is thought to be the 

 labrum or upper lip, and the membrane below it the epi- 

 pharnyx. The inner pair of stylets constitute the maxillas, 

 while the outer ones are the piercing mandibles. The proboscis 

 or rostrum is the labium or lower lip. 



The thorax, as in all insects, is composed of three segments 

 called respectively the pro-, meso-, and metathorax. Dorsally 

 however, only two of these segments are seen. The large por- 

 tion behind the head is the tergum or dorsal sclerite of the pro- 

 thorax and is called the pronotmn. The triangular sclerite 

 back of the pronotum is a part of the dorsal sclerite of the 

 mesothorax and is called the scutellum. The side pieces of the 

 thoracic segments are called pi'O-, meso-, and metapleurse, re- 

 spectively. 



The appendages of the thorax are the legs and the wmgs. 

 Each of the three segments bears a pair of legs and the meso- 

 and metathorax a pair of wings in addition. The legs have the 

 usual segments, but the tibise are very long and very charac- 

 teristically armed with a double row of stout spines. The tarsi 

 are invariably 3-jointed. 



The mesothoracic wings are thicker than the membranous 

 metathoracic wings. The former are often called the elytra 

 and a few speak of them as tegmina. In the accompanying 

 plate the different parts of the wing are labelled according 

 to the terms used in the following systematic treatise of the 

 Kansas species. The metathoracic or hind wings are some- 

 times simply called the wings. They are much wider than the 

 elytra and when at rest have the inner portion distinctly folded. 



