THE DIPT ERA. 
39 1 
are well shown in the case of the common house fly. The meta- 
morphoses differ, therefore, considerably in this very natural group. 
There are two great divisions in the order of the Diptera 
THE METAMORPHOSES OF THE GNAT. 
characterised by distinctions in the antennae ; the first section 
have thread-shaped and the second very short antennae, consisting 
of three very distinct joints, and a slender thread which is 
called a style. The first section, the Nemocera , have long and 
