THE AUCHBNORBHYNCHOUS HOMOPTBRA. 43 



to me and so far undescribed, are not discovered. I may, for 

 example, mention that in the Cercopidae, but not in the three 

 other families, the larvas have the abdominal pleural parts very 

 divergent from the adults ; in the same way the antennae in the 

 Cercopidse undergo a noteworthy change of structure, described 

 above, by which last-mentioned circumstance this family is dis- 

 tinguished from the other Auchenorrhyncha. That the larvae of 

 Stridulantia possess remarkably powerful anterior legs, adapted 

 for digging, is well known ; that, on the other hand, the structure 

 of their claws is totally different from that of the imagines is a 

 very peculiar fact not widely esteemed. For the lack of adequate 

 material I must, meanwhile at least, refrain from dealing further 

 with metamorphosis in the different families, and be content 

 with this intimation of its use for systematics. 



V. 



The principal difficulty still remains to be dealt with, viz. a 

 division into sharply characterized groups of these families, of 

 which th& Jassidae and'^ulgoridae have been so notably endowed 

 by nature with genera and species. Just so easy as division 

 and characterization of these families have appeared to me, just 

 so difficult did it appear to effect a dismemberment of the'3'assidae, 

 and jDarticularly of the'Fulgoridae, and that in spite of the fact 

 that surely not within a single family of insects are there found 

 such strong differences in habitus, in the form of the head and 

 prothorax, and in the structure of the wings, as actually in these 

 two. The material of the Copenhagen Museum, and that of it 

 that I could dissect for microscopical researches, was, particularly 

 in the^ulgoridfe, too meagre for sharp circumscription of groups. 

 I will now set forth my opinions, with constant reference to 

 Stal's above-mentioned (on p. 28)* proposals in * Hemiptera 

 Africana.' 



C 1. Stridulantia. — It appears to me very probable that this 

 family is susceptible of division into good groups. Stal has 

 scarcely essayed this. The division into two groups, based upon 

 the flight-organs, by Amyot and Serville, is perhaps a practical 

 help in identification ; but it is seen to be without scientific value, 

 as in the first little group there are placed such extremely diverse 

 genera d^s Poli/neura, Westw., a,nd Cystosoma, Westw. (as well as 

 the certainly highly mtevesting Ilemidictya, Burm., unknown to 

 me), separated from forms with which they have far stronger 

 relationship than mutually with one another.! 



*^ 2. Cercopidce. — Stal's groups in the * Hemiptera Africana' 



* Not translated.— G. W. K. 



f Dr. Hansen wishes me to say that at the time of writing these, he 

 was not aware of the existence of Distaut's ' Monograph of Oriental Cicadidae,' 

 1889-92 (a work scarcely to be found in Denmark), where this family is 

 divided into two primary groups, based upon the covered or uncovered 

 (speaking generally) condition of the tympana (p. 3). — G. W. K. 



