BY FREDERICK A. A. SKUSE. 665 



yeai'. They seem to chiefly haunt shady situations, and have 

 been frequently found in caves associated with Cecidomyidse, 

 Tipulidse, etc., but never to my knowledge have they been seen to 

 voluntarily attach themselves to cob-webs in the manner observed 

 amongst their near relatives, the gall-gnats ; on the contrary, I have 

 frequently taken both struggling and dead specimens from webs. 

 A large number of Sciaridae may be found flying about underneath 

 ■dense bushes, on logs, round tree-trunks, and amongst grass, but 

 as their habitats are for the most part umbrageous, these small, 

 often minute, sombre-coloured flies are rendered difiicult of detection, 

 and consequently their collection is scarcely an easy matter. An 

 inspection of windows generally rewards the collector of Diptera 

 with an abundance of small flies, especially if the windows over- 

 look a garden or rural expanse ; I have in this way obtained in 

 one afternoon specimens of a score or more species, the Cecido- 

 myidse and Sciaridse being chiefly represented. Insects which 

 could otherwise be followed only with a remote chance of success, 

 even by one possessing remarkably acute eye-sight, are readily 

 seen on a window, and their capture is easily accomplished. The 

 flight of the Sciaridse greatly resembles that of the Cecidomyidae, 

 and it is often impos.sible to distinguish between the two, more 

 particularly if the individual be small. 



With regard to the geographical distribution of Sciaridte, I 

 might mention that examples of the genus Sciara have been 

 recorded from all the great continents, and many islands more 

 or less remote from the mainland. They appear to be generally 

 difiused over the earth's surface, occurring in arctic, temperate 

 and tropical regions. About thirty species have been named from 

 North America, and almost as many from South America; others 

 are known from Africa, South Asia and the Eastern Islands, and 

 Professor Hutton has described one species from New Zealand. 

 According to Van der Wulp, Sciara thomcc, Linn., a European 

 species, occurs also in Sumatra. Of the other genera only one, 

 Trichosia, as far as I know, has been detected out of Eui'ope, 

 with a single species from North America, and another described 

 by me in the present paper, Imt, this far from demonstrates a 

 restricted range. 



