15S [Marcf/ 



cies; the thoracic pair was bifid.) The locomotive organs consist of more 

 or less apparent transverse swellings on the under side of the ventral 

 segments, sometimes furnished with minute bristles or spines. The latter 

 are frequently arranged (especially in Mi/cetophiJa) in two transverse, 

 parallel rows on each of eight or ten segments; in Bolitophila, if suffici- 

 ently magnified, they appear to consist of a multitude of short bristles, 

 arranged in lines, and forming a transverse band. The arrangement of 

 these bristles seems to vary in difi"erent species, and has been used by 

 Dufour as a specific character in the description of the larvae of several 

 Mt/cetuph'dse. Myc. inodesta Dufour, according to this author, had no 

 such bristles; likewise the locomotive swellings of all the Sciarse which 

 I have examined, had none; however, Sciara ingenua Duf. had them, 

 according to the same author. The larva of Sciojyhila which T reared was 

 furnished with them, but they were exceedingly minute ; they were placed 

 on the ventral side of eight abdominal segments; all rows being double, 

 except the first, which seemed simple; the 8th or last, was almost obsolete. 

 The last abdominal segment of the larvae is generally simple, but often, as 

 in some larvae of Mi/cetophUa, more or less bilobed. 



The larva of Cet-oplatus, judging from the descriptions of Reaumur, 

 Bosc and Dufour, has a very difierent structure of the body. Its four 

 anterior segments only are distinctly separated, the incisures of the others 

 being concealed by numerous transverse wrinkles, which give this larva 

 the appearance of a leech (see fig. 20). No stigmata was perceptible. 



II. PUPA. 



The pupjB uf the MijrttoplLilidte. are ('xtruatcd ; that is, not encased in 

 the contracted skin ol' the larva. The legs are applied to the breast and 

 venter; the antennae bent round the eyes, and their remaining portion ap- 

 plied to the breast between the wings and the legs. In Sriara their basis 

 is frequently expanded into a tooth. The prothoracic stigma is placed on a 

 small protuberance a little above tlie root of the wing, immediately behind 

 the antenna. In some Sciarse, this protuberance is extended into the shape 

 of a pointed horn, the direction of which is parallel to that of the longitu- 

 dinal axis of the body (fig. 22); an air-tube may be distinctly seen enter- 

 ing this horn. The abdominal stigma are distinct on both sides of the 

 abdomen, in the shape of small, brownish, nipple-shaped projections. 



These pupai are smooth, the margins and angles (jf the body are rounded, 

 and not sharp or pointed, like those of the pup;e of Ttpidufse, for instance. 

 Tlie only exceptions I met with arc those mentioned : th(! prothoracic 

 horns in some species of Sriinn. aisd the (loiilile point on tlie top of tlu^ 



