2 MB. F. WALKER ON THE DIPTEKA 



unknown : — Mycetopliilidas, Cecidomjzid^e, Bibiomidse, Simulidae, 

 Chironomidse, Phlebotomidse, HeteroclitaB, EhypMdae, Empidse, 

 ffistridfe. 



The gnats or mosquitoes (or CuUcidcs) are represented in these 

 isles by 12 species of Cidex, 2 of Megarhina, and 1 of Anopheles. 

 The genus Ciilex is found througliout the world, and has probably 

 continued from very early ages as compared with many other 

 genera of insects. The species of different countries have much 

 mutual resemblance, with the exception of a few that are peculiar 

 to warm regions ; and it is remarked by Humboldt that in some 

 parts of South America each stream has its peculiar species. The 

 genus MegarJiina is especially South American, and does not 

 appear in Africa, nor on the continent of Asia, nor in Australia. 



Tipulidce. — Of the seven genera in the following list, two 

 (JLimnohia and Tlpida) are distributed throughout the world ; and 

 tlie Limnohice here recorded are very few, and it is probable that 

 there are numerous undiscovered species in the eastern isles. 

 Limnobia is a remarkable group, on account of the variation of 

 the structure of the wing-veins being nearly equal to the number 

 of species, which is very great. It will be divided into very nu- 

 merous genera; and Baron Osten-Sacken has taken the lead in 

 this part of systematic entomology with regard to the North 

 American species. He has discovered in North America several 

 species which in England are represented by Qeranomyia ; and he 

 regards these as the remains of an earlier creation, which has 

 mostly passed away in Europe, its former existence being indi- 

 cated by fossils. Geranomyia is a native of the sea-coast, and is 

 found, with OrphnepMla, in the Channel Isles and in the western 

 parts of Q-reat Britain ; and these two genera, like the little Ohiro- 

 nomus that hovers over sea- weed, may have lived on the shores of 

 the former Atlantic continent. The species of Tipula and of 

 'Pacliyrhina here recorded are few in number, and are not peculiar 

 in structure. Megistocera is an Australian genus, and is remark- 

 able for the very great length of the antennge of the male. The 

 species in this list has been long known as a native of Java ; and 

 Mr. Wallace has discovered it in Aru. Ctenophora is generally 

 distributed ; but T^terocosmus is a new genus, founded on five spe- 

 cies from Borneo ; and Gymnoplistia, which was before orAy known 

 in Australia, is represented by three species. 



Stratiomidce. — This family is very diversified in the isles, and is 

 represented by 26 genera, of which 16 are new. The species of 

 these new genera are of comparatively small size, and in them the 



