480 



NEUROPTERA 



C the position of the wing on the exterior of the body is due 

 to the stripping off of the chitinous integument, or to a process 

 of eversion, or to both. 



FIG. 324. Development of wings 

 of Phryganeidae. (After Dewitz.) 

 A, Portion of body-wall of 

 young larva of Trichostegia : 

 eh, chitin, forming at r a pro- 

 jection into the hy- podermis m ; 

 r and d forming thus the first 

 rudiment of the wing. B, The 

 parts in a largely grown larva ; 

 , c, d, b, the much grown hypo- 

 dermis separated into two parts 

 by r, the penetrating extension 

 of the chitin ; v, mesoderm. C, 

 Wing-pad of another Phryganeid 

 freed from its case at its change to 

 the pupa ; b, d, outer layer of the 

 hypodermis, m, of the body- wall ; 

 r, inner layer without nuclei. 



' There are about 500 species of this family of Insects known as 

 inhabiting the European region, and about 1 5 of this number occur 

 in Britain. These are arranged by M'Lachlan ] whose zealous 

 and persevering work at this neglected family of Insects is beyond 

 praise in eight sub-families, on a system in which the structure 

 of the maxillary palpi plays a principal part ; they are called 

 Phryganeides, Linmophilides, 

 Sericostomatides, Leptocerides, 

 Oestropsides, Hydropsychides, 

 Ehyacophilides, Hydroptilides. 

 The first three of these form 

 the division " Inaequipalpia." 



Phryganeides. This group 

 includes the largest forms of 

 the family, and appears to be 

 almost confined to the tem- 

 perate regions of the northern 



FIG. 325. Cases of British Trichoptera. A, 



hemisphere, though a few Species Of Odontocerum albicorne; A 1 , its ter- 

 mination ; B, quadrangular case of Orun- 

 oecia irrorala ; B 1 , mouth of case. 



are already known from the 

 corresponding districts of the 

 southern hemisphere. This feature 



in their geographical dis- 



1 Monograph of the British Trichoptera in Tr. cut. Soc. London, third series, vol. 

 v. 1865 ; and Monographic Pievision of the European Trichoptera, 1874-1880. 



