MYCETOrillLTD.E. 385 



black with a white stripe on the iiiesonotnni, the metanotuiu 

 mid flanks being white, and tlie legs banded with white. It is 

 a widely diffused species, 

 and presents a most sin- 

 gular appearance when fly- 

 ing, as it moves slowly, 

 with its feet variegated 

 with snow-white, and extending like the radii of a circle. (Os- 

 ten Sacken.) In the genus Protoplasma (Fig. 306, wing) there 

 are six posterior cells in the wing. P. Fitchii O. Sacken is 

 brownish gray, with brown bands on the wings. 



Mycetophilid.e Macquart. This family comprises small 

 flies, capable of leaping to a considerable height, and provided 

 with two or thi-ee ocelli, but not having a proboscis. While 

 the antenna; are usually simple, as in all other Diptei'a, those 

 of PlatyroptUon Mlersii "Westwood arc forked, having a 

 branch one-half as long as the antenna itself. The thorax does 

 not have a transverse suture, and the wings are without a discal 

 cell, while the coxie are greatly elongated, and the tibiai are all 

 ai'med with spurs. The larvae are subcylindrical and smooth, 

 with locomotive bristles beneath, and eight pairs of stig- 

 mata ; they are in color white or j-ellowish. They are gregari- 

 ous, living in decaying vegetable matter, fungi, or in dung, one 

 species forming a gall. They shed their skin several times be- 

 fore becoming fully grown. Osten Sacken states that the larva 

 of Scioj)hila which covers the surface of the fungus it feeds in 

 with a web, is long and almost serpentiform, while those of 

 Boliiophila and 2[i/cetopJiila are shorter and stouter, and that 

 of Sciara is intermediate. The pupjB of tliis family are 

 smooth, with rounded angles and edges, whereas those of 

 Tipula are sharp and pointed. They are enclosed in a silken 

 cocoon. Some species of Sciara do not, however, spin cocoonr. 

 The larva of 3Ii/cetophila scatophora Ferris '"carries on its 

 back a sheath formed of its own excrements and moulded hy 

 means of a peculiar undulatory motion of the skin. The 

 pupoc remain Avithin the sheath, but before assuming this state 

 the larva extends the sheath anteriorly in a short neck, and 

 tapestries it on the inside with a pellicle, which renders it- 



