324 



ORTHOPTERA 



apparently in making use, not of a general inspection, but of a 

 scrutiny of the outlines of the leaves and twigs of a tree. By 

 this means, when the eye is accustomed to the task, the Insects 

 can be detected with comparative ease ; much in the same way, 



M. Boutan says, as a figure, placed 

 in an engraving in such a way as to 

 elude the eye, is appreciated with ease 

 after the eye has once perceived it. 



Some of the Locustidae are pro- 

 vided with means of defence of a posi- 

 tive nature. The Algerian Euyastev 

 guyoni ejects two jets of a caustic 

 orange-coloured fluid from two pores 

 situate on the sides of the meso- 

 sternum, and covered by the anterior 

 coxae. This species is carnivorous as 

 well as herbivorous, and produces a 

 sound more like humming than stridu- 

 lation. 1 



We have previously pointed out 

 that some of the Acridiidae resemble 

 the stick - Insects rather than the 

 members of their own group ; and 

 similar cases occur amongst the Locus- 

 tidae. Such a resemblance has, how- 

 ever, only been found in a few species 

 of the tribe Prochilides. We figure 

 one of these, Phasmodes ranatriformis, 

 a native of South - West Australia. 

 The very elongate linear form and the 

 total absence of alar organs give this 

 Insect a considerable resemblance to 

 the stick -Insects or apterous Phas- 

 midae. Prochilus australis is allied 

 to this curious Locustid, but the alar organs are present in both 

 sexes, and the Insect bears a great resemblance to the winged 

 Phasmidae. This is due not only to the general form and colour, 

 but also to the fact that the tegmina are very narrow, which 



FIG. 200. Phasmodes ranatri- 

 formis, female. Australia. (After 

 West-wood. ) 



1 Bonnet and Finot. Rei: Sci. Nat. (3) iv. p. 345. 

 as humming is " bruissement. " 



The word we have translated 



