Objects for the Microscope. 137 



hovering over the long grass, and may be recognised by 

 its black and yellow body, and peculiar darting to and fro 

 from flower to flower. The fore-tarsi are often dilated in 

 the male Empidae, but those of E. stercorea are not so. 



THE WING. The wing of Empis stercorea will give an 

 excellent example of the veining peculiar to the family. 

 They are distinguished by these three variations : 



1. The costal vein vanishes suddenly at the tip of the 

 wing, just where it meets the cubital vein. 



2. The cubital vein is forked. 



3. The discoidal areolet emits three veins to the interior 

 border. 



The wings of Leptis and of Asilus have also a forked 

 cubital vein, and three branches from the discal areolet ; 

 but they have other veins crowded together, which are 

 wanting in the Empis wing, and as the antennae are quite 

 as important to the entomologist in determining a genus 

 as the veining of the wing, by comparing those of a Leptis 

 with those of the Empis, a striking illustration will be 

 obtained of the progressive order and variety of likeness, 

 and yet of distinct difference, between the families. 



HILARA. 



By the wing and the antennae we recognise one of the 

 Empis-flies, but a variation in the form of the third joint 

 and the shortness of the first two joints is the first remove 

 from the true Empis. Observe also the stout, short pro- 

 boscis, and if it is a male Hilara the fore meta-tarsi are 

 much dilated, forming quite a disc on that part of the leg. 



How beautifully the wing is ciliated, the cubital vein 

 forked, the discoidal areolet emitting three veins, and a spot 

 upon the costal vein called the stigma, which in this wing 

 is marked by a broad brown shade. 



These Hilarae feed upon smaller insects, and also on the 

 nectar of flowers. They assemble in swarms, and dance 

 together over a rivulet or river, on fine, warm summer 

 evenings. We have often seen them rejoicing in merry 

 play, rising and falling in graceful evolutions, sometimes 

 by one common impulse sweeping off down the stream, as 



9 



