1862.] 161 



among the fragments of the decayed fungus. Dufour's observations 

 agree with mine. Guerin, as will be shown below, mistook for BoUtu- 

 phila quite a different larva. 



SCIOPIIILA. 



The larvae of this genus are easily distinguished from those of Myceto- 

 phila by their more elongated form and their mode of life, as they do 

 not burrow inside of the fungi, but live on the surface, generally on the 

 side of the pileus, which they cover with a web. 



Some of them are found on decaying wood, especially when it is covered 

 with hyssus. 



Degeer was the first observer of these larvae ; Dufour and Perris came 

 next. At present the transformations of Sciopliilse of all the three divi- 

 sions of Meigen (A, B, C) are known, and all seem to share the same 

 habits. Perris reared Sc. unimaculata Macq. (Div. B, Meig.) ; the same 

 author, as well as L. Dufour, reared Sc. striata Meig. (Div. A), and I 

 obtained in the same way Sc. Umhatella Zett. (or a closely allied species 

 of the same division C Meig.). The concurrence of these observations 

 makes me believe that the statement of Van Roser, who found the larva 

 of S. marginata Megerl. in an agaricus, and described it as being " ex- 

 actly like that of Mycctopliila^^ must be founded on a mistake; it will be 

 shown below that larvae of both genera frequently dwell together in the 

 same fungus. The following is an account of my own observations on ' 

 Sciophila : — 



I had brought home (in St. Petersburg, Russia, in Sept., 1855) larvae 

 of Mycetophila., which I succeeded in raising. Not less than 120 speci- 

 mens came out. What remained of the agarici, after this, was a putrid, 

 shapeless, semi-fluid mass, spread over the earth laying at the bottom of the 

 box in which the experiment was made. On these remains I soon noticed 

 minute larvae, diligently engaged in spinning; they grew rapidly, and in 

 five days were almost full-grown. During this time they had spun over 

 with a delicate web the whole surface of the putrid mass, especially the 

 hollows and inequalities in it. Each larva had its own district, where it 

 contined working under cover of the already completed tent. The latter 

 consisted of a dense upper stratum, under which hung, like so many 

 suspension-bridges, the tracks of the single larvae. On these tracks, 

 marked by a slimy substance, the larvae glided rapidly, like on a rail, 

 forwards and backwards. When disturbed, they immediately backed and 

 disappeared in their hollows. Sometimes they turned round without 

 leaving the track, by doubling the body and sliding the head towards 



