﻿283 



for leaping or running very quickly; thus dimorphism is strong- 

 ly represented amonp- Orthoptera and Auchenorhynohous Sip- 

 honata; and indeed in the Miridae, the great part of t'he dimor- 

 phic species have thickened posterior legs, as is also the case 

 with the femora in t'he Anthocoridae. 



(3) There are a great number of instances where the female 

 alone is dimorphic, but never a one where the male alone is so. 

 In such cases the female very often has the femora more thick- 

 ened than are those of the male — lamong Heteropterous 

 Miridae.] 



(4) Most dimorphic species live on 'herbs or near the roots 

 of such like. 



(5) On the contrary, no dimorphic species live on trees or 

 bushes. 



(6) In some cases, dimorphism depends so obviously on the 

 manner of living of the species that it cannot be caused by the 

 climate, for example, in certain Myrmecophilous species. 



(7) 'Not a single dimorphic species has been found among 

 the numerous fossil Orthoptera and Hemiptera. 



Renter therefore concludes: 



(i) The inacropterous is the primitive form and the brachy- 

 ])terous forms are only produced in a more advanced period by 

 "natural selection"; the existence of a macropterous form of 

 a species usually brachypterous must be regarded as reversion. 



(2) The reduction of the flight-organs is probably produced 

 l:»v diveise causes; in certain Myrmecophanous Miridae, it evi- 

 dently depends on the manner of living of the species and 

 "mimicry"; the Anthocorid Mynncdobia colcoptrata mimics Alexia 

 pilifcra, a little Coleopteron. [It should be noted however that 

 many Formicicolous insects do not at all resemble their hosts 

 or jailors.] 



(3) Many species have lived in localities where they liave not 

 l)ecn obliged to resort to flig^ht, because instead of trees and 

 I)us'hes the.v have lived on the ground or among herbs, thus 

 using their legs more often. Consequently in successive gener- 

 ations, the latter are continually developed more stronglv, while 

 the muscles of flight by lack of usage are generallv enfeebled 

 and atrophied, the tegmina and wings thus becoming as much 

 shortened as the legs are developed and thickened, l3y the law 

 of "reciprocal influence." 



(4) The male, as the active sex, has been obliged to avail 

 himself of his organs of flight, and exerc'se his muscles; this is 

 why this sex, in manv species, has, by heredity, the tegmina and 



