Marshall. — On New Zealand Diptera. 229 



wing-fold generally has its position just in front of the third 

 longitudinal vein, and often partially encloses the latter, or, 

 less frequently, obscures it entirely from view. No species 

 has more than one transverse or cross vein, which lies be- 

 tween the first and second longitudinal vein ; but it is fre- 

 quently most indistinct, or sometimes altogether wanting. 

 Abdomen elongate, composed of nine segments ; in the male 

 cylindrical, provided with large holding-forceps ; in the female 

 acuminate, with a proti'uding or non-protruding ovipositor, 

 rarely without two small lamellae. The whole body with a 

 covering of fine, delicate hairs, or less frequently scales or 

 scaly hairs, the latter occurring more often on the under-sur- 

 face of the abdomen and legs. 



The prevailing body-colours seem to be shades of yellow 

 iind red, darkening into brown proportionately as the integu- 

 ment becomes more horny. The expanse of the largest 

 species exceeds four lines, while that of the smallest is less 

 than a line. Regarding the relative numbers of the two 

 sexes, the females seem to be far more abundant than the 

 males. 



Classification. 



Skuse gives an excellent summary of the systems of classi- 

 fication of this family that have been adopted by previous 

 authors, and for information on these I must refer to his 

 paper. The following is the classification he adopts, and the 

 one that will be adopted in this paper : — 



Sub-family I. Gecidoviyina. 



Wings with not more than four longitudinal veins, the 

 two last frequently combining in the beginning of their course, 

 forming a more or less distinct fork. No ocelli. First tarsal 

 joint much shortened. 



Genus 1. Heterapeza. 



Antennae moniliform or sessile, 2 + 8 or 9 jointed. Legs 

 short ; third joint of tarsus very long. Wings with two 

 longitudinal veins. 



Genus 2. Miastor. 



Antennee 2 + 11 jointed, verticillate in the male. Legs 

 slender in male, but more robust in female. Wings almost 

 bare, with three longitudinal veins. 



Genus 3. Cccidomyia. 



AntenuaB long generally, verticillate, 2 -f 9 to 2 -f 36 

 jointed. Wings with three or four longitudinal veins. 



Section I. Wings with three longitudinal veins, the third 

 either forming a fork or becoming more or less obsolete 

 towards the tip. 



