secondary characters in the Diptera 477 



It consists of a straight edged lobe {A, Fig. 4) which is highly 

 chitinized and has the margin beset with a very close even row of 

 (tiny stiff bristles, co-planar with the lobe, the bristles having the 

 utmost regularity of size and shape : they form a perfect comb with 

 the teeth nearly touching. (3) In most dohchopids the squama con- 

 sists of a more or less pronounced knob bearing a characteristic 

 row of bristles, which are frequently spread out into an elegant 

 fan. In the present species the squama {S, Fig. 4) is long stalked, 

 apparently mobile, and instead of the usual fan of long hairs, it 

 carries a set of parallel stout bristles hooked at the tip. The relative 

 position of the last two structures almost irresistibly calls to mind 

 the relation of a hand to a harp. In the figure only one structure 

 is shown on each side to avoid confusion. (4) The fourth structure 

 {B, Fig. 4) is even more remarkable: it consists of a pair of large 

 spheroidal bodies, one on each side of the basal segment of the abdo- 

 men and confluent below with the hind epimeron. Each is hollow 

 and has a round orifice on the dorsal surface; from the bottom 

 springs a rod which nearly reaches the surface of the sphere. The 

 significance of the whole complex is entirely problematic, though 

 it is certain that the several parts are in some way duly correlated. 

 The general appearance, as said above, is that of some musical 

 instrument, although the function of the bulbs is quite problematic, 

 to suggest ' resonators ' is too fanciful, nor can one see the relation 

 of the whole to the remarkable wing form. 



It is much to be regretted that the paucity of specimens and 

 the fact that none but pinned individuals were available rendered 

 it impossible to submit the bulbs to a competent histologist, as 

 a suitable examination might have helped to throw some light on 

 this assemblage of mysteries. 



