2 Mr. Westwood's Observations on the Genus Derbe. 



of the reverend author. In describing these two genera, Mr. Kirby pointed 

 out their relationship both to Fulgora and Delphax, omitting, however, all 

 mention of the Fabrician genus Derbe, which is far more nearly allied to them 

 than either of the two genera which he notices. The genus Derbe was, how- 

 ever, evidently unknown to him, as it was also to Latreille and most subse- 

 quent authors. In the ' Systema Piezatorum' this genus is composed of eight 

 species, seven being inhabitants of South America, whilst the eighth is a native 

 of New South Wales, and was described from the Banksian collection, now in 

 the possession of this Society. Such, however, is the rarity of the species of 

 which this genus is composed, that no individual belonging to it existed until 

 very recently in the collections at Paris, nor am I aware of any other speci- 

 men in our English collections, except those in my own cabinet, subse- 

 quently described. 



In 1832, M. Percheron, a Parisian entomologist, who has especially directed 

 his attention to the Homoptera, Neuroptera, and other neglected orders of in- 

 sects, being desirous of obtaining a more perfect acquaintance with the genus 

 than is to be gained from the Fabrician description, applied to M. Westermann 

 of Copenhagen, by whose kindness he was enabled to publish a figure of the 

 Fabrician specimen of D. pallida, in M. Guerin's < Magasin de Zoologie.' 



It happens unfortunately, however, that the species thus illustrated does not 

 accord with the typical species of the genus, which therefore still remains 

 unfigured. Subsequently M. Boheman, instigated by the same desire of rein- 

 stating this genus in its proper situation (and evidently unaware of M. Perche- 

 ron's figure), published a memoir in the Transactions of the Royal Academy of 

 Sweden for the year 1837, in which he described several African species which 

 he considered to belong to the genus, but which also differ as greatly from its 

 true type as the species figured by M. Percheronf. 



On various previous occasions I have endeavoured to establish a fixed prin- 



t Since this Memoir was read, the Marquis Spinola has published a very elaborate Memoir on the 

 ft**** ■ the 'Annales de la Societe Entomologique de France/ for 1839, in which he forms the 

 genera ^e (descnbmg, ex visu, D. pallida, figured by Percheron), Otiocems and Anotia, into a distinct 

 subfamdy winch he terms Decides. TW are the only groups in the subfamily with which he wa 

 Kcqu amt d, an d f which the structure of the different parts of the head is principally emplo ed I 

 m throughout Ins memoxr,) for the discrimination of the different genera. Jj. W fL^jIM 



