440 



GNATS OR MOSQUITOES — CHAPTER XIII 



indivicluiil winf^s may vary to such an extent in one species as to render 

 characters of this sort, deduced from the exairiination of a few specimens 

 only, of but little value, except in a general way. In one instance the 

 riglit and left wings of the same insect (of C. pipiens) did not agree ; two 

 differences, however, proved to be constant. First, in C. 2n2nens, 4 is 

 close U21 to 3 (about its own length internal), while in C. fatigana they 

 are well separated (seldom less tlian twice the length of 4 apart). 

 Secondly, in C. piinens the anterior fork cell is fully five and a half 

 times the length of its stem, while in C. fatigans it is proportionally 

 shorter (not less than four and a half times its stems' length). The two 

 figures given below are chosen as the nearest alike that I could find 

 in my own small collection. 



Pig. 45. — Pa, venation of wing of C. pipiens ; Fa, of C. fatigans ; Qa, 

 relative position of fork of II. to aux. junct. in C. qiiasipipiens (the upper), 

 as contrasted with that in C. pipiens (the lower outline) ; Pb, head and appen- 

 dages of C. pipiens ; Fb, those of C. fatigans; Pc, group of outlines of wings 

 of C. pipiens to illustrate their variability. (These last not at staudard mag- 

 nification, but reduced from figures in Mr. Theobald's monograph.) 



In certain specimens there may be some indications of 

 thoracic ornament, but as a rule there is no definite adornment, 

 80 that I believe Wiedemann's description must be taken as 

 applying to the denuded thorax only. At the same time some 

 varieties exhibit more or less distinct true scaly decoration. 



Mr. Theobald describes the following sub-species, some of 

 which have already appeared as distinct species : — 



A. Type. 



Abdomen dusky black, with basal pure-white bands and basal 

 white lateral spots ; pleurie and metanotum chestnut-brown. 



13. Sub-species luteoannulatus. 



Abdomen dusky black or brown, with basal flaxen-curved bands 

 and pure white lateral spots ; pleur:ie and metanotum chestnut- 

 brown : thorax with traces of two parallel bare median Imcs. 



