May, 1916] Homopterous Studies. Part II 319 



an unusual state for the Homoptera, as Kershaw has shown that 

 in the Fulgorid Pyrops candelaria, the structure and morphology 

 of the nervous system is essentially the same. The abdominal 

 ganglia have probably migrated forward and fused with the 

 thoracic ganglia, leaving the abdominal commissures in their 

 former position. 



Circulatory System. 



The Circulatory System so far as observed, consists of a 

 long tube, or dorsal vessel, which runs the full length of the 

 body, from the brain to the last abdominal segment. In 

 general it is an undifferentiated tube, in which the blood 

 circulates. The pulsation of the dorsal vessel may be observed 

 by placing a living specimen under the binocular microscope, 

 and watching the rhythmic movements of the abdomen. The 

 vessel reaches the brain, which it supplies with blood and then 

 apparently divides into two branches which pass into the 

 body cavity. 



Conclusions. 



The studies enumerated above have led me to the con- 

 clusion that the Jassoidea can be homologised w4th the other 

 Homopterous families. The head differs very little from the 

 fundamental and generalised plan of the Cicada, and while the 

 Jassid does not show the development of the prominent sulci, 

 the structure of the mouthparts and head is very similar. 

 The mandibular setae represent the mandibles and the maxillary 

 setae, together with the maxillary plate constitute the maxillae. 

 While for systematic purposes we have been applying general 

 terms to the regions of the head, it would seem impossible 

 to change the nomenclature, so as to correspond with the morph- 

 ological details. The labrum and clypeus are scarcely dis- 

 tinguishable from one another and the epipharynx is closely 

 related to the labrum. The tentorium is present and the 

 invaginations occur as in all insects. There is a well-developed 

 salivary pumping apparatus. The epicranium is subject to 

 some modification in size. There is a well developed nervous 

 system, which is almost entirely cephalo-thoracic. The digestive 

 system, in the development of a food-reservoir agrees with the 

 other Auchenorrhynchous Homoptera. In general the plan 

 and morphology of the internal organs follows that of a gen- 

 eralised Hemipteron, and the various modifications which occur 

 in structure are just as likely to be specific as well as generic. 



