48o 



NEUROPTERA 



C the position of tlie wing on the exterior of the hodr is due 

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

 of eversion, or to both. 



Fia. 324. — Development of -wing-s 

 of Phryganeidae. (After Dewitz.) 

 A, Portion of body-wall of 

 young larva of Trichostegia ; 

 c/i, chitin, forming at r a jiro- 

 jection into the hypodermfs m ; 

 r and d forming tlms the first 

 rudiment of the wing. B, The 

 parts in a largely grown larva ; 

 a, c, d, h, the much grown hypo- 

 dermis separated into two parts 

 by r, the penetrating extension 

 of the chitin ; i\ mesoderm. C, 

 Wing-pad of another Phryganeid 

 freed from its case at its change to 

 the pupa ; &, d, outer layer of the 

 hypodermis, m, of the body-w.all ; 

 £", inner laver without nuclei. 



There are about 500 species of tliis family of Insects known as 

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

 in Britain. Tliese 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, Limnophilides, 

 Sericostomatides, Leptocerides, 

 Oestropsides, Hydropsychides, 

 Ehyacophilides, Hydroptilides. 

 The first three of these forni 

 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 

 hemisphere, though a few species 

 are already known from the 

 corresponding districts of the 

 southern hemisphere. This feature in their geographical dis- 



^ Monograph of the British Trichoptera in Tr. nit. Soc. London, third series, vol. 

 V. 1865 ; and Monographic Pvevision of the European Trichoptera, 1874-1880. 



Fig. 325. — Cases of British Trichoptera. A, 

 Of Odoniocerum albicorne ; A^, its ter- 

 mination ; B, quadrangular case of (Jrun- 

 oecia irrorata ; B^, mouth of case. 



