160 [March 



" chestnuts, singly, 20 or 30 on the same fungus. Before depositing 

 " them, she generally walks along the root of the fungus, in order to find 

 " the proper location for them. The larvae appear after 8 or 10 days, 

 "and begin to burrow in the underside of the pileus; they shed their 

 " skin three times, and transform near the outer margin ; the pupa state 

 " lasts from 9 to 12 days, after which the fly comes out, generally in the 

 " morning; it begins to move about to take its first food only towards the 

 " evening. 



" The eggs are one fifth of a line long, cylindrical, white." 



The larvae of this genus are generally whitish, rather stout. The horny 

 head is more or less brown. 



Myc. signata Meig. (? or a closely allied species), which I have reared, 

 also spun its cocoon without leaving the fungus. In order to ascertain the 

 relative proportion of the sexes in the perfect insect, of which I had ob- 

 tained a large number, I examined a himdred specimens and found 51 

 males and 49 females. The cocoon was truncated at one end, and this 

 truncature covered with a delicate web, which the fly breaks through in 

 escaping. In this, as in all other respects, Dufour's statements about 

 M.hilaris Duf. (syn. M. arcuata Meig ?), a species closely allied to M. 

 signata^ agree exactly with mine. 



A very curious larva of the same genus has been observed by Perris 

 (^Myc. scatopliora Perris). It carries on its back a sheath formed of its 

 own excrements, and moulded by means of a peculiar uudulatory motion 

 the skin. The larva is more stout and convex than the other larvae of 

 the genus, otherwise it agrees with them. The pupa; remain within the 

 sheath, but before assuming this state the larva extends the sheath ante- 

 riorly in a short neck, and tapestries it on the inside with a pellicule, which 

 renders it more tough and resisting. Larvae and pupa) were found on a 

 meadow, under an old plank, the under side of which was overgrown with 

 byssus. 



]5remi observed a similar larva, but referred it to Sriirpln'In. The 

 probable origin of this error will be explained below. 



CORDYLA. 



The larva of (J. <tassij>a/j)(( Dufour, observed by this author in a 

 fungus, seems to agree in every respect with the larva of Myrctophild . 



BOLITOPHILA. 



The habits of this genus seem to be like those of MycctophUu. The 

 larva spins a cocoon, which remains on the surface of the ground or 



