316 



known from several spots between Fiji and China. Othei- 

 species have au equally wide range. 



In working over a collection of Delphacidae from different 

 zoological regions one soon notices that there are numerous 

 cases of parallel development, both in structure and coloration, 

 which has no phvlogenetic significance. The expansion of the 

 legs in Asiraca and Fliyllodinus. and of the antennae in 

 Asiraca copicerus, Delphax and Puroliita, the reduction of 

 both wings and teginina, are a few such cases in structur(\ 

 In coloration it would be possible to draw up a long list, of 

 which the following are a few : Light carinae of head and 

 thorax with darker intercarinal spaces ; light spots on the 

 face ; light i)ronotum with dark mesonotum ; a dark spot on 

 metapleuruni ; rings and longitudinal marks on legs; a median 

 mark down frons, vertex and thorax ; a dark mark at end of 

 clavus and at end of costal cell ; these marks are often joined 

 l)y an ill-defined band; and the "crescent" pattern on apical 

 half of tegmen. This last consists of a mark from costa over 

 cross-veins, along hind apical nuirgin to apex or beyond; this 

 pattern with an increase or decrease of infuscation, with hya- 

 line spots at the end of the apical cells and with the other 

 apical veins also fuscous, forms the markings of a great num- 

 ber of species of which the following list is but a few: Stohaera 

 concinna, Sogatopsis praifi, Baiiihiisihatii.s alhoUncatiis, Del- 

 phax crasulcornis, Perlxlnh'ieJla rariefpita, P. pallidula. Pliyllo- 

 (llnvs 'Utaraoensis. Aticrlopia mdndane, Kelisia ficlx'n, Bake- 

 rella niarnlafa. DicnDiofropis l-ocJx'Jci. D. psciidonididls, Pcre- 

 grinus maidis, Del pJi a codes J'nidxrta. 



I caunot accouut for these cases of ])arallel (kn'elopment 

 on any utilitai'iau ]»riu('ij)al and if I must classify the pr(X'ess 

 it must be under some form of orthogenesis, which may give us 

 a name but not an explanation. 



Before the s])ecies of the genus Dei pliacodes and its allies 

 can be straightened out it will be necessary to make more use 

 of the genitalia than has been u]) to the ])resent ; not only the 

 pygojihor, anal seginent and genital styles but also the aedeagus 

 must be used. The last-named organ, I believe, will give us a 

 better idea of I'clationslii]) fluin any other single character. 



