126 Objects for the Microscope. 



woods, the meadows, the leaves of trees, or act as scaven- 

 gers to remove the noxious substances in the field or by the 

 wayside. 



There are twenty-eight families, each containing many 

 genera and species, which can only be learnt by long and 

 careful study, with the help of such works as ' Walker's 

 British Diptera' ; but we can very easily become familiar 

 with those which are thus mounted, and, through them, with 

 others which flit as yet unheeded around us. Nor will it 

 be long, I hope, before some small manual of the Diptera is 

 published, more attainable to the young student than the 

 one already mentioned. 



THE SCATOPIIAGA, 



(Ster cor aria,} 



is the common Dung-fly, seen all the year round, but 

 especially in summer, resting upon cow-dung and deposit- 

 ing its eggs therein. It is also often on the window- 

 panes. The male has a round hairy abdomen, the female 

 a naked pointed one. They are yellowish or olive-green 

 flies, the head yellow between the eyes, and with black 

 drooping antennae; thorax brownish above with four darker 

 stripes ; the wings are grayish, with a tawny tinge along 

 the veins. 



This preparation is very valuable, as showing the 

 antennae well. We perceive the very different structure 

 from those of the Gnat or Tipula. There are only five 

 joints visible, although six are reckoned by naturalists. 

 The third joint (reckoning from the base) is twice as long 

 as the second, the fourth obsolete, fifth and sixth seated 

 upon the third like a bristle, and called the arista. The 

 head of Scatophaga is very bristly, as you see ; and so also 

 are the legs, which we may next observe. The eye and 

 tongue of a fly are fully described under the slide of Head of 

 Rhingia, or Syrphus. The joint of the leg nearest to the 

 body is the coxa, the next to that the femur, or thigh, then 

 the tibia, or shank, and then the tarsi, or small joints 

 immediately above the foot. To see the foot well requires 

 a higher power, that the delicately fringed pulvillus may be 



