DIPTERA, 139 



beneath, running parallel, from the outer sides of 

 which arise numerous nearly parallel branches. These 

 tubes and their branches are incomplete beneath, and 

 consist of imperfect rings, otherwise greatly resembling 

 tracheae. On each side of the proboscis is a lip-feeler 

 or labial palpus , for the organ represents the labium 

 of other insects. All these parts are better seen in 

 the proboscis of the blow-fly than in that of the house- 

 fly, on account of their larger size. The head, the 

 thorax, and the abdomen are very distinct in the fly, 

 being separated from each other by well-marked con- 

 strictions. 



The legs are composed of five parts, each having a 

 separate name. The first piece or joint, which is 

 that attached to the body, is called the hip, or coxa ; 

 the next is a very small, somewhat triangular piece, 

 and is the trochan' ter ; next comes the long and stout 

 thigh, or femur ; this being succeeded by the tib'ia, 

 which, as in most insects, is furnished with strong 

 spines at the end ; and lastly is the foot, or tar'sus, 

 consisting of five joints, the three last of which are 

 represented in the figure (PL X. fig. 32) . At the 

 end of the fifth or last joint of the tarsus (fig. 32) 

 (for it must be noted that the joints of the limbs of 

 insects are always numbered in order of distance from 

 the body) are two soft little cushions, or pulvil'li, 

 which are covered on the under surface with numer- 

 ous hair-like bodies dilated at the end, acting as 

 suckers in enabling the fly to adhere to smooth sur- 

 faces. In addition to these organs are two curved 

 claws, and between them a sharp straight spine. 



The eggs of the fly are deposited upon heaps of de- 

 caying animal and vegetable matters, as dungheaps, 

 &c. The blow-fly deposits its eggs in the same situ- 

 ations, but especially those where the animal matters 

 are most abundant : every one knows the eggs as de- 

 posited upon tainted meats, when they are called fly- 

 blows. When the eggs are hatched, the larva or 



