702 



CLASS IV. INSECTA. 



jointed branchial filaments on each segment of the abdomen, which ends 

 in a median unsegmented style. The pupa is quiescent and the imago 

 lives but for a few days. Corydalis and Chaidiodes are giant forms and 

 the former often has the mandibles of the male enormously enlarged. 



With exception of a few 

 South American forms the 

 family is confined to the 

 Northern Hemisphere. 



Fam. 2. Raphidiidae. 

 The posterior part of the 

 head and the pro -thorax 

 are elongated and nar- 

 rowed, producing the ap- 

 pearance of a long neck. 

 The female has a long 

 ovipositor. The Snake- 

 flies are confined to 

 Europe, Asia and North 

 America. The larvae are 

 carnivorous and prey 

 upon insects frequenting 

 the old and rotten wood 



in which they live. The 

 FIO. 446. The Alder-fly, Sialis lutarict. Britain. A with . 



wings expanded ; B in profile. From Sharp. pupa, which in appearance 



is mid-way between a larva 



and an imago, becomes active before it gives exit to the latter. There are 

 but two genera, Raphidia and Inocellia with a fair number of species. 



In the remaining families, the mandibles and maxillae are characteristi- 

 cally coadapted in the larva to form piercing and sucking organs. 



FIG. 447. a Myrmeleon formicarius ; b its larva. 



Fam. 3. Myrmeleonidae. Antennae short and clubbed. The nervures 

 of the apex of the wing enclose regular oblong cells. Maxillary palp 

 5-segmented, labial palp 3-segmented. Nocturnal insects, whose 

 larvae are the well known ant-lions. The eggs are laid in sand, 

 and when the larvae emerge they prepare conical pits in sandy 

 soil and, concealing themselves at the bottom, seize and devour any 

 unwary insect which falls into their pit. The arrangement of their legs 

 necessitates a retrograde motion, and enables them also to throw sand upon 

 their victims to aid their descent into the pit. The prey is grasped in the 

 stout mandibles ; these have grooves in which the maxillae play to and fro. 



