Syrphidae. 31 



it has only a pharyngeal skeleton. Above and at the sides of the 

 body are always some larger spinules or warts; they may be very 

 small and slightly pronounced (I thlnk partly dependent on the con- 

 traction of the dermis) or they may be somewhat larger or be deve- 

 loped into longer filaments, as in the first group of the species of 

 Syrplms; they often bear branched hairs or spines. They are always 

 arranged in a certain way; the prothoracal segment has generally 

 some, either more or less numerous spinules ; on the meso- and meta- 

 thoracal segments and on the first abdominal segment there is on 

 each a transverse row of six spinules; on the other segments they 

 are placed thus that there are two in the middle on one corrugation 

 and two towards each side on the foUowing corrugation; when the 

 segments are less distinctly divided into corrugations, the spinules or 

 warts may be all placed on one corrugation, but however the two 

 lateral on each side more posteriorly than the two median ; at the 

 sides each segment has three spinules, generally one above and two 

 more downwards, besides there is generally one more ventrally. On 

 the last segment they are also present, but the arrangement is here 

 various. The spinules or warts are, as said, always present, and the 

 longer filaments often present at the sides of the last segments, belong 

 to them and always answer to them in number, but when these seg- 

 ments are much elongated the arrangement is effaced; also the threads 

 on the sides of the tail-shaped part in the larvæ of the Eristalinae, 

 and the filaments surrounding the posterior margin of the body in 

 the Volucella-lsirva. belong to the same category. Only in a single 

 case (some Volucella-Vdrvæ) there are, besides the mentioned spinules 

 or warts, some more. Many larvæ have below pairs of prolegs armed 

 with spines, generally six or seven pairs. The larvæ are amphipneu- 

 stic with generally small anterior spiracles at the hind margin of the 

 first thoracai segment, and with posterior spiracles on a shorter or 

 longer posterior process on the last segment, sometimes situated at 

 the end of a long, tail-shaped part. As the Syrphids are cyclorrhaphous 

 flies the pupa is a barrel-pupa; the larva pupates within the skin of 

 the last larval stage; the skin is contracted and altered in the well 

 known way, and in it lies the real pupa; the pupa with its enclosing 

 barrel or puparium is in the descriptions simply termed the pupa. 

 The pupa still shows the larval attributes, but the various spinules or 

 filaments, the prolegs etc. are generally shorter and less distinct; the 

 posterior spiracular process is present as in the larva (but out of 

 function). The prothoracal spiracles of the pupa behave, as mentioned 

 above, in different ways; in many species (most of the Syrphinae) 

 they do not protrude through the puparium and are thus not visible 



