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STUDIES IX LIFE-HISTORIES OF AUSTRALIAN" DIPTERA BRACIIYCEKA, 1., 



Close to the anus, ou each side, ami directed towards it, is a single short bristle. 

 Further back a jiair of bristles is situated on tiie ridge ou eacli side of the anal 

 groove, and another pair on the terminal apex ot the ridge, where it Ixiunds uie 

 transverse split (Text-fig. 8). 



Among these large bristles there occur on the body a few very small colour- 

 less bristles, about 0.05 mm. long. Eight of them are in constant a.ssocuitioii 

 with the bristles bounding the transverse split, in which the aperture of tracheal 

 chamber u]iens. Two are inserted above and two below the aperture, one close 

 beside the bristle at the angle of tlie split, and one between each pair of apical 

 bristles (Text-fig. 7) . A similar hair occurs laterally on both surfaces of every 

 segment, just beyond and below the outermost bristles of the transvei'se rows. 



Text-tig. 12. Anterior end of l:irv;i. Ventral view, (x 12). 

 Text-fig.i;i. ,. ,, Dorsal view, (x 12). 



Text-fig. 14. Prothoracic spiracle. Surface view, (x 112). 



Text-fig. 15. View looking down ou posterior end of larva, (x 22). /, terminid groove ; 

 s, spiracular aperture; i7, anus; D, dorsal surface; V, ventral surface. 



The arrangement of the bristles on the thoracic segments is somew-hat dif- 

 ferent. On the dorsal surface of tiie fii'st segment there are two transverse rows, 

 with four small bristles in the first row, six in the second (Text-fig. 13). Meso- 

 and nieta-thoracic segments each bear the usual row of six on the dorsal surface. 

 But on the ventral surfaces of tlie tlu'ee segments there are only four. On the 

 prothoraeic segment these are arranged in two rows, on meso- and meta-thorax 

 in a single row, with the two outer bristles directed forwards instead of back- 

 wards (Text -fig. 12) . The lateral ridges bear each only a single pair of long 

 bristles, but a small colourless hair, siuiilnr to the other microscopic liairs on 

 the bodv, is also present. 



Except in the relative length of llic bristles, the smallest larvae found (2 

 to 3 mm.) are exactly similai" to tlie fully-develo|ied larvae. The bristles are 

 proportionally much longer in the younger larvae, and give them a distinctly 

 hairy appearance. The two long bristles of the lateral ridges are specially well 

 developed, while the two smaller ones are very minute. 



The Head. — The head is short, and broadly conical, having a basal width 

 of 0.48 mm., and a length of 0.,57 mm. in larvae of 8 mm. length. It is deep 

 yellowish-brown in colour, darkest in front, where it is most strongly cliitinised, 

 and divided into a uiedian and two lateral lolies (PI. xxvii.. figs. 1, 2) . The 

 median lobe terminates in a small, cylindrical process, with smooth surface, and 



