LECTURE IX. 115 



in manner of life and place of residence, some 

 living on putrid animal substances, some on the 

 smaller insects ; and some are of an aquatic na- 

 ture. Some Flies, as a species greatly allied to 

 the common Window- Fly for instance, are ovi- 

 viviparous, producing living Maggots, which have 

 themselves been first hatched internally. 



The Common Gnat belongs to a genus called 

 Culetfy and is sufficiently known to supersede the 

 necessity of particular description. It deposits 

 its eggs in groupes on the surface of stagnant wa- 

 ters, and the young during their larva state are of a 

 very peculiar appearance. When changed into the 

 chrysalis state they are still loco-motive, and when 

 ready for the production of the perfect Insect spring 

 to the surface of the water, and give birth to it. 



In the genus called QEstrus or Gad-Fly the 

 eggs are laid by the parent insect in the skin of 

 the backs of Cattle, in one species; in others in 

 the nostrils and other parts of Deer and Sheep : 

 the larves, when arrived at their full size, creep 

 out, and retiring beneath the surface of the grass 

 or under any convenient body, change into a 

 chrysalis, from which in a certain space springs 

 tfye animal in its ultimate form. 



