284 



wings developed, while the female is dimorphic and rarely 

 macropterous. 



Renter divides polymorphic iorms into two kinds — 1 repro- 

 duce his classification, but not his polysyllabic nomenclature: 



(i and 2) Trimorphic and dimorphic forms, the latter sub- 

 divided into 



(a) Female only dimorphic, e. g. PerkinsicUa sacchanada. 

 (aa) Both sexes dimorphic, divided into 



(b) Male dimorphic in a different manner to the female, e. 

 0-. EnidcUa spcciosa. 



(bb) Sexes equally dimorphic, e. g. Percgrinns maidis. 



Renter further divides the forms according to degree of 

 shortening, as follows: 



(t) Brac'hypterous form has the tegmina either a little short- 

 er than, the same length as, or a little longer than, the abdomen, 

 and the apical cells most often moderately developed. 



(2) Tegmina at least a third s'horter than the a'bdomen, and 

 much shorter than those of the macropterpus forms; apical cells 

 short, obsolescent, or absent; wings rudimentary or wanting. 

 This section contains the majority of forms. 



The term 'brachypterous ranges through "microplcrous" from 

 "brachypfcrous" to "apterous." 



In comment on the above, it may be noted — 



( 1 ) That in the tropics there are certainly man\- dimorphic 

 leaf-hoppers arboreal. 



(2) There seems to be no difference, in leaf-hoppers, in the 

 structure of the legs in different forms of the same species. 



(3) Th effect of climate is very problematical, but it is likel\- 

 that in the tropics, brac'hypterous forms appear in the colder 

 season. As Perkins has well remarked: 



"One point in connection with this flig^htless forms is worthy 

 of notice. Although the insect has not been with us for study 

 for a sufficiently long time for us to speak with certainty on the 

 point, yet, so far, the worst attacks of leaf-ihopper have ahvays 

 followed or been partly coincident with the production of these 

 flightless females, that is to say durin'g the colder months of the 

 year, or in the early summer. 'In the course of my recent tour 

 of investigation through Hamakua to Olaa, T did not find a 

 single example of the short-winged form, while in the wintef 

 months from some plantations not less than fifty per cent of 

 the adults sent were of this form. This fact and some observa- 

 tions that I have made on other Hawaiian species, lead me to 



