154 [March 



diiFereuces of structure : a. In Sriara aud Myrctophila sigiHifa its an- 

 terior and posterior openings are almost connected, or separated only by 

 narrow, horny stripes; in some Sfi'ai-se, for instance, there are two such 

 stripes (fig. 3) ; in other but one (they seem to break oif easily, at least in 

 specimens preserved in spirits) ; b. In Sciujyhila (fig. 7, t') and the sup- 

 posed larva of Leja^ (fig. 8, t') the anterior and posterior openings are 

 separated by a broad portion of the shell ; a distinct longitudinal suture 

 in the middle of this interval, indicates the soldering together of the two 

 edges of the shell. As to Bolifophila, among my five specimens of its 

 larva, one has the edges of the shell connected, in the others this connec- 

 tion was broken, as was evident fi'om the irregular outline of the margins. 



Viewed in front (in the direction of the axis of the body) the head 

 generally shows the following openings in the horny shell, easily perceiv- 

 able on account of their paler color : in Mi/cctopliila (fig. 12) a sub- 

 triangular spot in the middle (r/), which is the fleshy part of the upper 

 lip ; a round spot on each side, (rudimentary antenna, fig. 12«) ; a second, 

 more oblong and irregular spot below (the interval between the root of the 

 mandible and the edge of the horny shell, fig. 12/i'* ; fig. 11, the inter- 

 val between /• and .s), and a third smaller spot (m) which is the ocel- 

 lus ; the three slits on the lower part of the head (?i*) are the intervals 

 between the maxillae. Sciophila has the same pellucid spots; but those 

 marked a and /.•* on the plate are oblong, and the spot (ocellus?) m is 

 black, opaque. Sciara is in this respect like Mijcctopliila^ only the spot 

 m (ocellus) is either black, opaque or wanting. In Bnlitophila the spot 

 d (labrum) is much smaller, a a (antennae), on the contrary, larger.* 



The organs connected with the head, and which I have to describe now, 

 are the luitennse, the ocelli and the parts of the mouth (trophi). 



A. Antennse. A pair of round openings in the horny shell of the head, 

 one on each side of the mouth, are the places of insertion of the antennse. 

 In Mycetophila they seem to be generally rudimentary, mere soft, fleshy 

 swellings projecting through a round hole (figs. 1 and 2, «) ; still, the 

 larva of Mj/r. nigra has, according to Bouche, distinct, stout, conical 

 two-jointed antenna), and Cordi/la o-dssipaljia ( according to Dufour) 

 likewise, although short ones. Srlura{ig. 4, a) and S<:loj)hlla (fig. 6, fO 

 have, like Mycetophila, rudimentary antennae. In BollfopJilla they reach 

 the greatest development, being distinctly jointed. They consist ol a 



* I deemed it useful to notice these paler spots on the dark ground of the head, 

 as former authors have mentioned them, without explaining their meaning. 

 Perris, for instance, has figured tJie liead of Seiopliila viewed iu tlie direction of 

 the axis of the bodv. 



