the Biology of some British Neuroptera. 505 



indistinct, but sometimes marked off as the anterior margin 

 of the clypeus. In the larva of the AustraHan Psychopsis 

 elegans (12) the labrum projects as a distinct lobe, and this 

 is also the case in Coniopterygidae, where it roofs the sucking 

 spears. The mandibles are almost straight, or curved, 

 often serrate at their apices. They are grooved ventrally, 

 and the edges of this groove are generally further grooved or 

 keeled to engage with complementary grooves in the maxillae. 

 The mandibles and maxillae when fitted together leave a 

 central channel along which the blood of victims can flow. 

 The two appendages are not fixed, but are free to move 

 upon one another longitudinally, in fact such movement 

 always occurs when an insect is being sucked. Probably 

 movement prevents particles from clogging the extremity 

 of the lumen. When this play of maxilla against mandible 

 occurs, the hinge joint between stipes and cardo of the 

 maxilla bulges out each time the latter is pulled back. 

 The extremity of the maxilla is generally blunt (not in 

 Coniopterygidae) and bears sense hairs. Since the larvae 

 have but poor vision, the sensitive tips of the maxillae are 

 used to search out food. The larva walks with a side-to- 

 side motion of the head, especially noticeable in Hemero- 

 biids, and thus brushes against aphids, etc., lying in its 

 path, with the sensitive ends of the maxillae. These aphids 

 are then sucked. The labium is always reduced, but is 

 provided with palpi, except in Sisyra. The eyes are 

 generally of six ocelli, but not always. Antennae are simple, 

 but vary in the number of joints. 



The body is soft. Terga may be complete (Sisyra) or 

 reduced to small sclerites, as muscle attachments {Hemero- 

 bius, etc.). The prothorax is of three more or less distinct 

 parts : (1) a small fore part rarely extended in life; (2) a 

 large middle portion bearing legs below and the main 

 sclerites, whatever they may be, above; (3) a small hind 

 division with a pair of spiracles laterally. 



The legs have a full complement of joints, but there is 

 a tendency to fusion of tibia and tarsus, complete in the hind 

 legs of Myrmeleonidae. The tarsus consists of only one 

 joint. There are two tarsal claws, one in Sisyra. No clue 

 is given by the first-instar Sisyra as to how this reduction 

 has taken place, but if evidence from the examination 

 of ant-lions can be accepted here, then the reduction has 

 been by fusion of two claws laterally rather than by loss of 

 one. Sisyra has no empodium, but in the other genera 



