430 NEUROPTERA 



other Insects. The earlier stages and life-histories of these 

 Insects are of great importance. The perfect Insects are so 

 delicate and fragile that they shrivel much in drying, and are 

 very difficult to preserve in a condition suitable for study. 



The mouth of the imago is atrophied, the trophi scarcely 

 existing as separate parts. Packard says that in Palingenia 

 bilineata he could discover no certain traces of any of the moiyth- 

 parts, but in Leptophlebia cupida he found, as he thought, the 

 rudiments of the maxillae and labium, though not of the mandibles. 

 The antennae are always short, and consist of one or two thick 

 basal joints succeeded by a delicate needle-like segment, which, 



though comparatively long, is 

 not divided. The ocular organs 

 are remarkable for their large 

 size and complex development ; 

 they are always larger in the 

 male than they are in the 

 female. The compound eyes of 

 the former sex are in certain 

 species, e.g. Cloeon (Fig. 274), 

 FIG. 274. Front of head of Cloeon, male, a, quite divided, so that each eye 



Pillared eye ; b. sessile eye ; c. ocellus. , ,, ,, 



becomes a pair ot organs ol a 



different character ; one part forms a pillar facetted at its summit, 

 while the other part remains as a true eye placed on the side of 

 the head ; in front of these compound eyes there are three ocelli. 

 Thus the Insect comes to have three different kinds of eyes, 

 together seven in number. 



The prothorax is small, the pronotum being, however, quite 

 distinct. The mesothorax is very large; its notum forms by far 

 the larger part of the upper surface of the thoracic region, the 

 metathorax being small and different in structure, resembling 

 in appearance a part of the abdomen, so that the hind wings 

 look as if they were attached to a first abdominal segment. The 

 mesosternum is also disproportionately large in comparison with 

 the homologous piece preceding it, and with that following it. 

 The pleural pieces are large, but their structure and disposition are 

 only very imperfectly understood. The coxae are small and are 

 widely separated, the anterior being, however, more elongate and 

 approximate than the others. The other parts of the legs are 

 slender ; the number of joints in the tarsi varies from five to one. 



