DixA. 259 



begins at the augle in the praet'urca, ahuost immediately turning 

 outwards and running straight to the wing-tip. Anterior cross- 

 vein short, placed just at the bend of the 3rd vein. The 4th vein 

 forks just beyond the anterior cross-vein, the upper branch forking 

 a^aiu near its tip, the lower branch straiglit, simple. Basal side 

 of 3i*d posterior cell rectangular ; disced cell absent ; posterior 

 cross-vein just beyond the base of the 3rd postei'ior cell. Pour 

 posterior cells. The 6th vein nearly sti'aight, the 1th vein absent, 

 or at least abortive, as there is a faint trace of a very short vein at 

 tlie extreme base of the hind angle of the wing. The venation is 

 remarkablv consistent in all the Indian species. 



Range. Europe, Morocco, Asia Minor, Siberia, Himalayas, 

 China, North America and the AVest Indies. 



So long ago as ITl'I Re'aumur described the larva of Dixa* 

 and De Geer t later on redescribed it, adding much further infor- 

 mation. 



Staeger has described the life-history (Keaumur's description 

 was of the larva only and not of the transformations) of a specie? 

 from Denmai'k, D. nigra. % The transformations of several 

 European species are described by Meinert. § 



The larva of Dixa has a habit of resting with its body in the form 

 of a siphon, that is to say, with its head and tail drawn up close 

 together, the intervening portion of its body curved into a loop, the 

 top of the loop being a little antei'ior to tlie middle of the body ; 

 in other words, the bend does not occur half-way between the ex- 

 tremities, but at the fifth and sixth segments behind the head. The 

 head has gi'eat flexibility, as it can be bent round parallel to the 

 rest of the body. It is hard, with a pair of branched antennae 

 and elongate, palp-like appendages about the mouth. There are 

 eleven segments to the body in addition to the head, the ultimate 

 segments bearing the caudal appendages, consisting of an elongate- 

 conical central piece which ends in three filaments, and two slender 

 flexible hairy side-pieces. The locomotive organs (pseudopods or 

 prolegs) are ventral, and not dorsal as has been stated by both 

 Reaumur and De Geer. They are armed with hooks, and are 

 placed on the fourth and fifth segments. On the eiglith, ninth, 

 and tenth segments are bunches of setae which fulfil the office of 

 legs, and were mistaken for such by Reaumur. In some species 

 the dorsal surfaces of six of the segments (the fifth to the tenth 

 inclusive) bear oval shields fringed with setae. In other species 

 this character is absent. 



The larva grows to a length of less than half-an-iuch. It is 

 found in pools overgrown with vegetation, resting on leaves just 

 above the surface of the water, and remains with its head and tail 

 close to the water's edge. If removed from the water it soon dies 



* Mem. de I'Acad. Roy. de Paris. 



t Mem. Hist. Ins. vi, p. 380(1776). 



> Naturh. Tidsskr. iv, p. 202 (1842). 



§ K. Danske Vid. Selsk. Skrift. iii, p. 452 (1886). 



