Eristalis. 411 



some longitudinal furrows. The dermis is tough and densely beset 

 with small spinules; besides these clothing spinules there are above 

 on the corrugations some a little lårger spines or small warts but they 

 are very slightly pronounced; they are present in the same number 

 and arranged quite in the same way as in other Syrphid larvæ so 

 that there are some on the prothoracal segment, a transverse row of 

 six on second and third thoracai segments and on first abdominal 

 segment; on the other segments there are two in the middle on one 

 corrugation and two towards each side on the next corrugation; on 

 the sides there are three on each segment, and one quite below on 

 the ventral surface. On the ventral side there are a pair of proleg- 

 like warts, beset with spines, on the prothoracal segment, and then 

 six pairs of prolegs on the six first abdominal segments; they are 

 beset with curved spines at the end, especially along the hind margin. 

 The last segment terminates in the long, tail-shaped part with the 

 posterior spiracular tube which is telescopically pro- and retractile and 

 able to be stretched out to a very great length. The tail consists of 

 three divisions, the foremost is a prolongation of the last segment, it 

 is transversely wrinkled and like the other dermis beset with fine 

 spines ; at the sides of it are four small bunches of hairs at intervals, 

 one at each side at the base, one at the apex, and two intermediate, 

 but the distances between them are dependent on the contraction; 

 the next division is thinner, longitudinally striated and with fine, 

 nearly microscopical spines in rows; finally the third division is still 

 thinner, more firmly chitinised and brown; it is very finely trans- 

 versely striated, the end part smooth, and it bears at the apex the 

 spiracles, surrounded by eight plumose hairs ^ The length of the 

 three divisions are dependent on the degree of extension, only when 

 fully extended they are seen in full length, and when fully retracted 

 the intermediate part is quite hidden in the basal division and only 

 the end of the third part is seen protruding from the first or basal 

 part, and also this latter part may be somewhat contracted. At the 

 hind margin of the prothoracal segment lie the anterior spiracles, they 

 form short, brownish, a little curved horns, but they may be quite 

 retracted and then only seen as points. Above on the first abdominal 

 segment two somewhat circular spots are seen ; these are the points 

 through which the anterior spiracular tubes in the pupa protrude. 

 The anus lies below in front of the tail; protruding from its opening 

 is sometimes seen a bundle of thread-like appendices, the use of which 



^ Miall follows Reaumur in stating that there are five hairs, but, as Trybom 

 correctly says, there are eight. 



