912 



FRESH-WATER BIOLOGY 



ing. A very ordinary sort of white fleshy legless fty larva has 

 the supporting base of the terminal spiracles drawn out into a flexu- 

 ous slender tube, as long as or longer than the body. The larva 

 lives in the mud in shoal water, and with this tube reaches up to 

 the surface for air. A good many aquatic forms are included among 



FIG. 1380. The crane-fly Epiphragma fascipennis, 

 adult female. 



FIG. 1381. Epiphragma: a, larva; b, 

 end of larva from above; c, pupa. 



the host of higher diptera that are here dismissed as Muscidae 

 in the broad sense, but the larvae of these (Fig. 1382) differ from 

 their terrestrial relatives by characters of less moment than those 

 just mentioned. 



A few small families are most interesting for their fitness for 

 special places in the water, both larval and pupal stages being 

 passed in similar situations. The net-winged midges (Blepharo- 



