BY W. R, COLLEDGE. 77 



pleura are often found denuded by rough contact with objects 

 in its somewhat awkward movements. Each scale is traversed 

 by a series of longitudinal ribs. These ribs being thicker than 

 the body create minute channels which are filled with air. 

 The specific gravity is thus reduced, and they are kept dry 

 during rain. The variety of shapes they assume is seen in 

 fig. 31. Some are curved I'ke boomerangs, others spatulate or 

 sword-like, a few are triangular, but the most are of the 

 battledore form with great variations in length and width. 

 Very strong spiny bristles, yellow, and fluted longitudinally 

 are scattered over various portions of the body, their roots being 

 recessed in hollow sockets formed in the chitinous covering of 

 the insect. 



The Halteres, 



of which one is represented by fig. 2 , are pale yellow, and 

 placed immediately behind the wings. Not much is known 

 about their functions, although there has been a good deal of 

 speculation on the subject. They are hingul at the base, and 

 when the insect is at rest, may be seen to move up to a 

 horizontal position, then slowly sink to the sides, the process 

 being repeated every few seconds. Probably the motion is in 

 unison with the perisaltic action of the intestines, and may help 

 in directing the current of air through the tracheal tubes. 



The Male 



is seen in fig. 35. Its body is narrower and longer than the 

 female, from which it is easily distinguished by the feathery 

 antennpe and long plumed palpi. The males are usually the 

 first to appear in any batch of eggs of the same age. They have 

 less vigour and succumb more easily to unsuitable conditions 

 than the other sex. The last segment is seen in fig 38. From 

 it two muscular lobes spring armed with long claspers. At the 

 base of these pillars on their internal aspect anotber pair of 

 hooks are placed with their curved points turned from each 

 other. They extend two-thirds the length of the lobes. Also 

 equidistant from the base of the pillars, a narrow central organ 

 arises ending in a double hook, whose points also turn away 

 from each other. The latter is likely an outer sheath for the 

 penis, and its hooks as well as the mid pair are probably for the 

 purpose of expanding the vaginal tube to ensure the passage of 

 the spermatic fluid during copulation. A very excellent descrip- 



