CORETHRA: EARLY STAGES 191 



male and pilose in the female; the first segment is globular. Palpi 

 four-jointed and reclining downwards. Proboscis very short, concealed, 

 and not formed for piercing. Thorax arched and projecting somewhat 

 over the head. Scutellum simple, never lobed ; metanotum arched. 

 Abdomen long and slender, consisting of eight segments. Legs long and 

 delicate, always hairy, and tibiae without spurs. Wing venation 

 typically culicine, scales only present on the wing fringe, and a few 

 of the veins, otherwise the wing surface is hairy. 



The genera of the Corethrinae may be recognized by the following 

 table modified from Williston's key : 



1 . Metatarsus shorter than the following segment , . . Corel h ra 



(Mochlonyx). 

 Metatarsus longer than the following segment ....... 2 



2. Large species (10 mm. or more long) with true scales on cross- 



veins and with bifid claws ....... Pelorempis. 



Small species, claws simple . . . . . . . . . 3 or 4 



3. Antennae with second segment long, spaces between verticils 



bare, true scales on distal parts of veins .... Ramcla. 



Antennae verticillate, veins devoid of scales, and only clothed 



with hairs .......... Chaoborus. 



(Sayomyia). 



4. Antennae with second segment long, spaces between verticils 



hairy Corethrella. 



Antennae with second segment short, spaces between verticils 



bare , Eucorethra. 



There appears to be some confusion regarding the synonomy of the 

 Corethrinae. The species which Lichtenstein (1800) named Chaoborus 

 antisepticus was only described in its larval stage, and it remains an 

 open question as to whether it was a true Corethra (C. plumicornis) 

 or not ; in any case, it seems a pity to change the well established and 

 familiar name Corethrinae to Chaoborinae, as has recently been 

 suggested by Edwards. 



The larva of Corethra is common in pools and ponds in Europe, and 

 is a well-known natural history object ; it is almost transparent, 

 and has been aptly named the ' Phantom larva'. It 

 lies horizontally extended on the surface of the 

 water, now and then suddenly whisking its posterior end and darting 

 after its prey, for it is predaceous. Its head is pointed anteriorly ; 

 antennae project over its mouth, and are armed at their extremities 

 with five long curved bristles. When not in use they are flexed on 

 the basal joint. The labrum is long and keel-shaped, and the mandibles 

 are armed with several strong teeth. It preys chiefly on small larvae, 



