68 



conspicuous, and as a rule long, 7vith but fe%v exceptions possessing four 

 membranous wings ivith many cross-nervures ; wings arising by 

 invaginations of the hypoderniis, and for some time remaining tucked 

 within the body. Metamorphosis complete, the pupa leavi?ig, or partly 

 leaving, the cocoon or other shelter before disclosing the imago. 



Even when thus restricted the Neuroptera display much diversity 

 of form and habits, and the various famiHes often succeed rather 

 well in hiding their relationships to one another. The families are : 



1. Sialidce. 6. Mantispidce. 



2. Raphidiidce. 7. ffetnerobiidce. 



3. Myrnieleonidce. 8. Chrysopidce. 



4. Ascalaphidce. 9. ConiopterygidcF. 



5. Nemopteridcc. 10. Panorpidcc. 



In some of these the family likeness is very pronounced, but in 

 others it is not so, and considerable further sub-division is necessary 

 before we arrive at genera and species. 



1. SlALIDA',. 



In Britain we have two representatives of this family, the very 

 common alder or orl fly {Sialis lutaria) (PI. V, fig. i), and a con- 

 gener (S.fuliginosa), which is much less frequent, and with difficulty 

 distinguished from it. Everyone has seen the former of these dusky 

 insects about May, either resting with wings arched over its back, or 

 flying with a slow, heavy flight. Its brown egg-batches, containing 

 a very large number of eggs, placed on the vegetation by the margin 

 of the water, are interesting, and so is the carnivorous larva which 

 may be dredged from the rubbish at tlie bottom of streams and 

 ponds. This larva has seven pairs of jointed appendages on the 

 ventral surface of the abdomen, which act as gills for breathing, 

 with which also the creature swims. When full grown the larva 

 forms a cell in the bank before changing into the pupa. This is 

 lively, but without leaving the cell becomes an imago, whose life in 

 the upper air lasts but a few days. While S. lutaria is everywhere 

 common, S. fuliginosa, its darker and perhaps later relative, seems to 

 be scarce, though it may have been overlooked to some extent. It 

 has been taken at Rannoch in Scotland, and in tiie southern part of 

 the island in Dorset, near Box Hill and near Haslemere at least. 



Only a few species are contained in the genus Sialis, which belongs 

 to the Patearctic and Nearctic regions^ though, strangely enough, it 

 occurs again in Chili. In the family Sialidae are also found the 

 genera Chauliodes and Corydalis, which consist of large insects very 

 unlike Sialis in appearance, though they have a very similar life- 

 history. 



2. Raphidiid^. 



Though the species are fairly numerous, two genera only com- 

 prise the family Raphidiid?e, Raphidia and Inocellia, both found in 



