Development of Lonchoptera. 341 



When the larva is full grown, it detaches itself from the skin, 

 which retains its form, and within which the insect changes into a 

 white, opaque, fleshy grub (PL XI. fig. 9), consisting apparently 

 of thirteen segments, which gradually diminish in size from one 

 end to the other. There are no limb-cases. The skin is covered 

 by small papillae. It is one-tenth of an inch in length. 



According to analogy the pupa should be "incomplete;" it is 

 probable, therefore, that the legs and wings make their appearance 

 at a later stage. If this be so, the perfect form is only attained 

 after passing through three well-marked stages.* I regret, how- 

 ever, that the specimens at my disposal did not enable me to 

 decide this point. 



When about to emerge it splits the old larva-skin between the 

 2nd and 3rd segments from a to a (PI. XI. fig. 1), and along the 

 back down the central line of the 3rd, 4th and 5th segments of the 

 body, from 6 to 6 (PI. XI. fig. 1). 



Mr. Westwood, while admitting the difficulty of the case, places 

 Lonchoptera with Platypeza in the Scenopinidce, close to the 

 DolichopidcB, and among the Tanystoma. Mr. Walker, though he 

 removes Scenopinus, and raises Vlatypesa and Lonchoptera into 

 two separate families, leaves them still in the same position 

 between the Dolkhopidce and the Syrphidce. In this classification 

 the nature of the metamorphosis is mainly relied on. In the 

 Notacantha (Stratiomys, Sargus, Beris, &c.) the metamorphosis 

 is coarctate, but the skin of the larva retains its form ; in the 

 Tanystoma {Tabanus, Anthrax, Asilus, Dolichopus, &c.) the pupa 

 is incomplete ; in the Athericera (^Musca, Conops, CEstrus, Syrphus, 

 Volucella, &c.) the metamorphosis is again coarctate, but the 

 larval skin contracts and hardens into a kind of cocoon within 

 which the transformation is effected. 



These differences are of much importance. " The great cha- 

 racter," says Mr, Westwood, " by which the Stirps {Tanystoma) is 

 distinguished from the Notacantha and Athericera, consists in the 

 nature of the metamorphosis to which all the species are subject. 



" The larvae resemble worms, being nearly cylindric, without 

 feet, and with a scaly head of a constant form, always furnished 

 with unguiforra retractile appendages, enabling them to pierce the 

 substances whence they derive their support : for the most part, 

 they reside under-ground, and are but little known. They shed 

 their skin previous to assuming the pupa state, in which, to 



* In a future memoir I hope to be able to show that this remarkable fact is not 

 so anomalous as it at first sight appears. 



