THE ATHERICERA. 367 



terminal joint is almost invariably furnished with a 

 bristle, generally arising from its dorsal surface, and 

 often close to the base. This bristle, however, is 

 usually composed of several joints, so that we may, 

 without much violence, suppose it to represent the 

 remainder of a multiarticulate antenna, and its sur- 

 face is frequently hairy, or even, as in the common 

 Fly, plumose. The proboscis is subject to some va- 

 riation, and frequently attains a great length, but it 

 is almost always capable of being retracted within 

 the cavity of the mouth, and its palpi are always 

 small, composed of a single joint, attached to the 

 basal portion of the proboscis, and visible externally 

 only when the proboscis is very much extended. 

 Under ordinary circumstances, they are to be seen 

 enclosed in the cavity which receives the proboscis 

 when completely retracted. The bristles enclosed in 

 the proboscis are but two in number in the majority 

 of these insects ; many, however, possess four of these 

 organs, whilst in one singular group all the organs 

 of the mouth become perfectly rudimentary. 



In their perfect state most of them feed upon the 

 sweet juices of flowers, very few being predaceous or 

 sucking the blood of the higher animals. Their larvse 

 are soft, footless grubs, generally of the form popu- 

 larly known as a maggot ; they live for the most part 

 immersed in the substance which serves them for 

 food, and never change their skin. This is also per- 

 sistent, as in the preceding tribe, after the change to 

 the pupa state, when it usually contracts into a hard, 

 brown, oval case. According to some observations of 

 Dr. Eeissig, published in Wiegmann's Archiv fur 

 Naturgeschichte, and in abstract in the 'Annals of 

 Natural History ' for April 1856, the process by which 



