the Biolog// of so)iie British Neuropfera. 511 



as specific characters and vary somewhat. The markings 

 of Coniopterygid larvae are almost entirely of this nature, 

 but the black markings of Semidalis larvae are due to hypo- 

 dermal pigment. In most larvae tliere is a dark median 

 longitudinal line which pulsates usually in a wave forwards, 

 but appearing to reverse once or twice every few minutes. 

 This is produced as follows. The dorsal vessel lies immedi- 

 ately under the skin, and is of transparent colourless 

 contents (blood). It is bounded laterally by opaque fat 

 body. Thus we have a transparent longitudinal window 

 through which the gut contents are visible in varying 

 shades of brow^n. The pulsation of the dorsal vessel accounts 

 for the occasional disappearance of this dorsal line. 



It is remarkable that a colour pattern will persist more 

 or less from larva, through pupa to imago, and that green 

 and red appear to be interchangeable pigments. This is 

 always more or less true, but strikingly illustrated in 

 ChrysojKi vulgaris. The larva has a dark crimson line on 

 either side of the central yellow area. The pupa has a 

 pink line on either side of a yellow dorsal vitta. Later 

 pink turns to green. Now the im.ago has a yellow dorsal 

 vitta bounded by darker green. Some forms in v/inter 

 become reddish, thus reverting to early pupal coloration. 

 Other examples could be given in Hemerobiidae, etc. 



The Larvae of Neuropterous families known to occur in 



Britain may be briefly tabulated as follows : 



A. Tarsus with one claw Sisyridae. 



(Entirely aiiuatic.) 

 AA. Tarsus with two claws. 



B. Empodiiim trumpet-shaped, conspicuous. Chrysopidae, 



and Ist-instar Hemerobiidae. 

 (Terrestrial.) 

 BB. Empodium not trumpet-shaped. 



C. Jaws short and inconspicuous, covered 



above by labium Coniopterygidae. 



Coniofterijg inae. 



CC. Jaws easily visible. 



D. Jaws inwardly curved Hemerobiidae. 



(Terrestrial.) 



lerobiidae. 



(Terrestrial.) 



DD. Jaws not inwardly curved, straight 

 or almost so. 

 E. Jaws elongate, slightly curved 



outwards. Larva amphibious. . Osmylldae. 

 EE. Jaws straight, needle-like. Larva 



terrestiial Coniopterygidae. 



A leuropteryginae. 



