AND DEVELOPMENT OF COMY.S IXFELIX. 251 



the back, extend a short distance beyond the end of the body ; this is true for the hind 

 wings as well as for the fore win^s. 



In colour, the male fly differs considerably from the female. The body is entirely 

 black, except several white joints of the legs. The thorax and head are dull black, and 

 not golden brown as in the female. The antennae are completely black, and do not end 

 in a club-like dilatation, for the component segments are almost equal in size. The 

 antennse of the male fly can also be distinguished from those of the female by the fact 

 that they possess a conspicuous covering of flne black hairs, relatively long ; the elbow, 

 too, is not so strongly marked as in the female antenna. When the male is looked at 

 from the side, it is seen that the antenute are arched upwards and forwards, the tips 

 curving dow^n again. 



The wings are, proportionately, much larger than in the female ; they differ also in 

 not possessing the shaded fuscous patches so noticeable in the other sex ; they are, on 

 the contrary, of a sliining iridescent colour, having an almost metallic appearance. The 

 group of hairs so marked on the surface of the female fore wings, is absent in the male, 

 in which the entire surface of the wing is covered with a soft down of fine hairs. 



The legs are similar to those of the female, the second pair being furnished with the 

 large tibial spur so characteristic of the species. 



The abdomen is relatively smaller than that of the female, but, as regards the arrange- 

 ment of the segments and of the curious lateral plates, the form is identical. The 

 reproductive apparatus differs entirely from that seen in the female. In the natural 

 condition, there is a small pointed process projecting from the tip of the body, on either 

 side of which can be seen a little wing-like organ. When dissected out, the male organs 

 are found to be composed of a central hollow piece, or penis (PI. 12. fig. 45, j5., h.), in 

 Avhich run the ducts communicating with the glands. On each side there is a jointed, 

 hooked rod, ending in three sharp teeth. Outside these parts, laterally, there is another 

 rod-like organ, which ends in a long spike, or seta. The tip of the penis has curious 

 little papilise, which are the openings of the ducts leading from the gonads. 



Xote. — "While performing the work recorded above, I have been fortunate in having 

 the valuable help of Dr. 1). Sharp, wiio has, Avitli constant generosity, given me the 

 benefit of his knowledge and experience ; I am, therefore, only too happy to take this 

 opportunity of acknowledging, with gratitude, the essential service he has rendered. 



Balfour Laboratory, Cambridge, 

 May 14tb, 1903. 



