18 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. [To?.V. 



PART II. 



]S"OTES Oi?^ APHIDIN^, WITH DESCEIPTIOi^S OF NEW SPE- 

 CIES. — J. MONELL. 



Siphonophora, Koch. 



Eostrum moderately long. 



Antennfe seOited on more or less conspicuous tubercles; longer or at least as long 

 .as the body; third joint long; first joint suboyliudric; seventh joint setaceous, 

 very much longer than the preceding ; trontal tubercles approximate. 



Nectaries long, subcylindric, slender. 



Style ( Cauda) long, of ten compressed, falchion-shaped. 



Legs slender, very long. 



Wings deiiesed. 



Front Avings with four oblique veins ; the cubitus twice forked. 



Hind wings with two oblique veins. 



So far as is known, tlie o^^parous females in this genns are always 

 apterous and tlie males winged. The males usually have smaller ab- 

 domens, larger wings, and longer antennoe than the viviparous winged 

 females. As in most other ApMcUdxe^ the antennae are, strictly speaking, 

 six jointed, the so-called seventh joint being merely a slender prolonga- 

 tion of the true sixth joint. 



Whatever opinion one may hold as to the characters that should be 

 considered of generic imi)ortance, the first requirement of a system of 

 classification must be practicability. In a family like the ApMdidce, 

 where the species are numerous and exceedingly difficult to study, I 

 should be inclined to accept any generic arrangement, however arbi- 

 trary, if it were but practicable. What Walsh said of species is equally 

 applicable to gejiera. The only A'^alid practical criterion of generic dis- 

 tinctness is the general non-existence of intermediate grades in the dis- 

 tinctive characters. Even granting that the existence or non-existence 

 of the frontal tubercles would be of generic importance, which I very 

 much doubt, the genera depending on this character must be united, as 

 they are connected by so many intermediate gradations that it is im- 

 possible to fix a limit between them. So little is known in regard to 

 these insects that for the present I prefer retaining the genera as gen- 

 erally adopted, as it Avould be useless, and only add to the confusion, to 

 propose a generic arrangement which future observations may overturn. 

 Though the connecting links between some of the genera have not yet 

 been discovered, yet, as these genera are based on comj)ai^ative, and not 

 absolute, differences, it is more than i^robable that future discoveries 

 will force us to unite most, if not all, of the genera of the ApliidinWj and 

 to readopt tlie generic arrangement given by Kaltenbach. 



Siphonophora achyraxtes, n. sp. — Apterous females : Pale green, with a dark irreg- 

 ular stripe on each side of the abomen; in fully developed specimens occasionally with 

 an additional short stripe near the basal xiart of the al^domen, extending over several 



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