1913J Kershaw — The Alimentary Canal of Flata ant other Homopfera 183 



seem to contain much waxy matter, and comparatively few urates. 

 But the malpighian tubes require much more study in long series 

 and at all periods from nymph, to adult. 



Whilst examining many adults of Siphanta acuta, one specimen 

 was found which had one tube completely and perfectly forked 

 distally, just as in Perkinsiella saccharicida. 



The malpighian tubes of the Homoptera mentioned in this paper 

 are not intricately mixed up with the fat-body and other internal 

 organs, nor so much tied and entangled with tracheae as in most 

 insects. The distal ends nearly always lie very near the extremity 

 of the abdomen. Occasionally the tubes are connected by the 

 tissue of their distal ends, generally in pairs, but their lumina do 

 not communicate. 



The tips of the setae of Siphanta do not appear to penetrate the 

 xylem of vegetation, but it is difficult to kill a specimen so that 

 the setae are left in the foodplant. The sketch given (fig. 5) was 

 made from a mealybug (I eery a purchasi). Several were feeding 

 close together on a young stem of a leguminous tree, and a piece 

 of this was suddenly plunged into benzene, which kills them 

 quickly. Some of the sections made showed the setae even more 

 twisted than those in the sketch. When the tips of the setae 

 encounter any hard obstacle they glance aside till they meet another 

 hard spot, again following the least resistance till they reach the 

 layers of tissue next the cambium. Some of the mealybugs had 

 penetrated the cambium, but none had entered (though one or 

 two had touched) the xylem. This might be expected, since all 

 the matters useful as food to the insect are contained in the tissues 

 external to the xylem: the contents of the latter being mere water 

 with mineral salts in solution. 



The tissues of the Eucalyptus trees on which these Flatids were 

 feeding contain a large quantity of oil and resinous-wax. Some 

 of these substances must be imbibed by the insects, and a great 

 deal of wax (more or less resinous) is excreted by them during 

 their nymphal and adult life. This wax is largely secreted and 

 excreted by anal wax-gland areas, but minute wax-glands are 

 scattered over almost all parts of the insect, even on the head 

 and wings. They are very numerous and rather large on the 

 claval area of the tegmina of Siphanta, and they occur on the tip 

 of the epicranium of Pyrops. The Membraeidae also have small 



