100 Mr. F. Balfour-Brownc on tlw 



Caiuera-luciJa drawings show that the thorax of //. ruji- 

 coUis, hei/deiii, and nomax is slin;htly wider in proportion and 

 that the sides are slightly more convergent, but it is sur- 

 prising liow slight in reality these difllertnces are. 



With regard to the form of the elytia I have spent much 

 lime in trying to make camera-lucida drawings of the different 

 species, but I found that the drawing seldom resembled the 

 niodel, and that even minute changes in the position of the 

 insect — slight raising of the anterior or posterior end — gave 

 an entirely different result in the drawing. There is, how- 

 ever, in spite of the impossibility of figuring it, some 

 difference, perhaps in curvature of surface and light reflection, 

 which is quite indefinable, but which is useful. 



But variations in form occur within a species, and the 

 members of one group approach and sometimes even overlap 

 those of the other. //. noma.v, for instance, seems to be 

 specially variable and some individuals are evidently ^videst 

 across the middle of the elytra. H. rnficoiUs and loehnckei 

 also vary somewhat, so that caution is necessary in making- 

 use of this character. 



The Elyteal SxEiiE. 



Edwards divides the species into two groups according 

 as "the dark lines 1-4 [are] unequal in width, distinctly 

 widened on the disc, 5-7 interrupted at the base, in the 

 middle, and at the apex, and often confluent," or " 1-4 of 

 uniform width throughout, 5-7 less decidedly or not at all 

 interrupted," and in this character I find some variation, 

 especially as regards H. wehnckei and also in H. nomax which 

 ^vas unknown to Edwards. 



It is often very difficult to determine the females of 

 //. icehnckei as distinct from those of //. ru/icoliis, but males 

 of the former not infrequently show elytra! lineation of the 

 same type as that described for the latter, and females, which, 

 on the majority of characters, belong to the former, even more 

 frequently on this character should belong to the latter. In 

 //. nomax the majority would belong to the "7'iificolUs" 

 section, but some have a clear lineation which would place 

 them with the ^' loehncTcei^' section, and in this species at 

 least the extent to whicli the black overflows the lines and 

 runs into patches varies greatly in different localities. 



In all the species there seems to be a tendency for the 

 black lines to break up, but it is, I think, rarest in //. apicalis 

 and H. immaculatus. This character is not therefore of great 

 value in separating the species, although us an indicator it is 

 frequently useful. 



