Objects /or the Microscope. 131 



the eye sees often the heart feels. Find out, therefore, a 

 very short and oblique vein, between the cubital and the 

 prcebrachial, down close to the dot of the radial, and the 

 space thus bounded at the base is called the prcebrachial 

 areolet, and its minute size and position in every one of the 

 genera is decisive of the family. 



Pass on now to the legs, and remark the spines on the 

 femora and metatarsus ; they will also serve to show the 

 species, for in some Dolichopus there is invariably but 

 one spine, in others four or two, and in some there is a 

 double row. 



THE OPOMYZA 



is one of a family group called Geomizides ; they frequent 

 recent or decaying vegetable substances, also our windows, 

 and are very present little unknown friends. We may 

 know these by their spotted wings, by the tawny body, 

 yellow head, thorax striped with three pale lines; the 

 abdomen has a dark dorsal stripe or dark bands; they 

 abound in herbage. Now examine the head and wings. 



The head is broad and eyes large ; the antennse, like 

 those of a true Musca, three joints drooping, the third 

 round and large ; the arista long, slender, hairy, and with 

 a small joint you will hardly see unless the head is in 

 profile. 



The thorax is bristly ; the abdomen has seven segments 

 a little hairy ; and then pause to look at the wings, and 

 compare them with those of Dolichopus. 



You will first observe two transverse veins slightly 

 clouded ; the prcebrachial straight ; the discal transverse 

 hindermost, and joining the pobrachial vein to the prce- 

 brachial ; the cubital and radial veins are quite straight. 



CHLOROPS. 



A mischievous little Fly ; and the farmer will be inter- 

 ested in seeing the parent of that larvae which sometimes 

 commit such havoc in his wheat-field. In England there is 

 a disease known as the gout, from the swelling it occasions 



