282 



the head of this species and briefly describe it on a subsequent page 

 of this paper under the heading Genus incertus 2. 



Subfamily HEXATOMINAE 



SUBFAMII^Y CHARACTERS 



Larva (PI. XXXIV, Fig. 14). — Very slender; aquatic or semi- 

 aquatic. Head flattened, not so heavily chitinized as in other sub- 

 families (PI. XXXIV, Fig. 12). Maxillae with a long, slender, 

 pointed process at outer anterior angle, the processes having been er- 

 roneously designated as maxillary palpi by some authors. Antennae 

 short and slender. Labial plate not chitinized, indistinguishable. 

 Mandibles long and slender, sickle-shaped, the teeth confined to base 

 or basal half of inner surface. Body without distinct pseudopods, 

 usually covered with silky hairs; apical segment terminating in 4 

 slender processes which are fringed with long fine hairs (PI. XXXIV, 



Fig. 13). 



Pupa. — Head produced in the form of 2 wart-like protuberances 

 at bases of antennae, bases of the latter, especially in male, swollen, 

 their apices extending to or beyond apices of wings. Thoracic respira- 

 tory organs long and slender, sometimes acute apically; legs extend- 

 ing well beyond apices of wings. Abdomen with a few weak hairs, 

 the segments, except the basal one, usually with a preapical dorsal 

 transverse band of small spinules. 



HABITS OF IvARVAE 



The larvae of this subfamily are aquatic, but usually, as is the case 

 with other aquatic Limnobiidae, they pupate in the mud alongside the 

 stream in which the larvae occurred. The food consists of algae and 

 vegetable debris. 



HABITS OF IMAGINES 



The imagines of this subfamily which we have observed, are m.ost 

 active in the late afternoon, flying in swarms over streams or along 

 their margins. Usually they are sluggish, and may be swept from 

 rank herbage along stream margins. I do not know their food-habits. 



Keys to Genera 



LARVAE 



1. Lower process on each side of apical abdominal segment with a very 

 long terminal hair in addition to the fringe of short hairs along 

 margin Pentliopfcra. 



