7. MACHIMUS 671 



the other liairs on the back of the head, even to those just beliind the vertex, 

 are yellow and fine and long ; bristles about the ocelli rather long and black^ 

 but those at the sides of the brownish yellow frons shorter and arranged in 

 two irregular rows, and the uppermost ones black but the others usually soon 

 becoming aliuost all pale yellow ; frons on its middle part bare and blackish ; 

 collar yellowish, bearing pale pubescence and about two (2-6) strong though 

 inconspicuous yellow bristles on its upper part which (when numerous) form 

 a strong chevaux de frise. Proboscis shining black, with short obscure 

 pubescence round its tip and very long yellow hairs beneath near its base ; 

 palpi with long nearly all yellow hairs. Antennae dark brown, but the two 

 basal joints rather obscured by grey dust; basal joint with short sparse 

 depressed pale yellow hairs above and numerous long bristly hairs beneath 

 which may be all yellow but which are usually partly black ; second joint 

 with only short pubescence which is mostly pale with black hairs intermixed 

 or vice versa ; third joint about as long as the two basal ones together, and 

 bearing a few short black bristles above soon after the base ; style set at an 

 angle with the third joint, and from about half to two-thirds its length. 



_ Thorax yellowish grey with the usual dark stripes ; the blackish brown 

 middle stripe very distinct, widening anteriorly, and with an evident (though 

 sometimes faint) grey middle line which may be anteriorly as broad as the 

 dark sides of the stripe, and the sides of the middle stripe may have still 

 blacker outer margins, but posteriorly the middle stripe contracts rather 

 suddenly into a narrow dark brown line at about midway between the suture 

 and the scutellum ; side-stripes most perceptible when viewed from behind 

 when they contrast with the yellowish grey stripes, and these yellowish grey 

 stripes almost coalesce soon after the suture ; humeral stripes only visible 

 at their front end as small dark brown spots ; humeral space covered with 

 whitish grey dust which extends over, and to just below and behind, the 

 humeral knob ; in fresh specimens the side stripes are very indistinct, but in 

 older specimens they become more distinct through being rubbed and then 

 they sometimes have darker margins on their inner side; when seen from 

 above the side-stripes usually appear broad (though sometimes very vague), 

 beginning about half-way between the front and the suture and extending 

 (in some lights) broadly but vaguely to the hindmargin. Pubescence on 

 the disc short, all black, and not very bristly but becoming longer 

 and thinner-haired towards the hind part, while pale yellowish thin- 

 haired pubescence occurs on the humeri, just before the wing-base, 

 between the wings and the scutellum, and on all the postsutural part of 

 the disc. Bristles conspicuous; praasutural two strong and yellow and a 

 smaller remote black anterior one ; supra-alar three, all yellow ; postalar two 

 long and yellow- dorso-central about four postsutural rather strong and 

 yellow but only distinct through the black spots from which they rise as 

 otherwise they are liable to be mixed up with the surrounding long 

 pubescence, while any prtesutural are small and black and hardly distinguish- 

 able from the neighboring bristly hairs. Pleurae yellowish grey, with pale 

 pubescence on the prothorax and the space beneath it, on the upper part of the 

 mesopleurge, and sparsely on the upper part of the sternopleurte and ptero- 

 pleurae, while the metapleural fan is composed of rather dense very long and 

 rather strong (but not bristly) hairs and the hypopleural fan of four or five 

 similar long hairs. Scutellum bearing rather short dense whitish yellow 

 pubescence,_ and with several (4-8) long conspicuously pale yellow marginal 

 bristles which are erect or rather curved forwards • metanotum light grey, 

 and bearing some short pale pubescence on the side numps. 



Abdomen (when seen from above) grey with dark reflections along the 

 sides, or (when seen from behind) greyish black or greyish brown, with pale 

 yellowish grey or whitish grey hindmargins of segments and sidemargins, and 

 (in certain lights) with a slightly darkened dorsal stripe ; the pale hind- 

 margins are narro^v about the middle but curve up towards the broad whitish 

 or yellowish grey sidemargins ; when seen from in front the abdomen anpears 

 to be all yellowish grey down to the blackish genitiilia ; pubescence on the 

 disc short and all pale except for sometimes some black hairs about the 

 middle of the hindmargin of the last segment ; basal segment with a prse- 

 hindmarginal fringe of pale hairs which become almost long bristles at the 



