510 Syrphidae. 



longitudinal folds ; above on the corrugations are slightly larger, scarcely 

 perceptible, divided spines, which are arranged regularly above and 

 on the sides in the usual way; the prothoracal segment has numerous 

 small spines at the anterior margin, and at the sides outwards to the 

 anterior spiracles two groups of small spines. The head is small and 

 retractile; above the mouth opening are the two-jointed antenna-like 

 organs, each ending v^rith two small papillæ; at the hind margin of 

 the prothoracal segment lie the very small, brown anterior spiracles 

 at each side; towards the end of tlie tapering posterior part are at 

 each side three filaments one behind the other, the last placed at 

 each side of the apex; they are clothed w^ith relatively iong hairs, 

 and the hairs on the posterior part of the body are upon the v^hole 

 longer than those on the anterior part; at the posterior end is a 

 short, about 0,7—1 mm Iong, brown posterior spiracular process, 

 bearing the spiracles on the flat end surrounded by stellately arranged 

 fine threads, On the ventral side are six pairs of prolegs, arm ed with 

 spines, on the six first abdominal segments, and below the prothoracal 

 segment a pair of similar spined warts; the anus lies relatively Iong 

 forwards at the beginning of the tapering part and somewhat before 

 the side filaments; it is thus seen that the last segment is Iong and 

 thai it is this segment alone which bears the side filaments; these 

 latter answer also in reality to the lateral spines found on the other 

 segments; several of my specimens show the same bundle of threads 

 protruding from the anus as was mentioned under the EristaUs-\sir\a. 

 The colour of the larva is yellow or whitish yellow, the length about 

 12 mm. The pupa is brownish, rather arched, almost not attenuated 

 in front as the front end is declining downwards; it has the same 

 posterior spiracular process as the larva, and likewise the side fila- 

 ments but these latter are shorter; at the hinder border of the declining 

 front part are two 1 mm Iong, brown anterior spiracular tubes; they 

 are approximated at the base, directed upwards and a little back- 

 wards; they are beset with small tubercles, placed ring-like. The 

 length of the pupa is about 9 mm. — The larva of X. nemorum is 

 similar to the above description, but the larger, regularly arranged 

 spines are here larger, rather conspicuous, and brown, and at each 

 side of the prothoracal segment outwards to the anterior spiracles is 

 a large, black, bifid spine, such as figured by Perris for X.pigra, but 

 differing by the outer hook being the larger, while in pigra the inner 

 is the larger; these spines are not found in the larva oisegnis, which has 

 here only groups of small spines. The length is about 9 mm. The pupa 

 is likewise similar, the anterior spiracular tubes are a little shorter 

 and thicker, and less approximated at the base, and at the lowcr 



