I04 



The Fly of Chironomiis 



considerably lower level : a deep groove separates the 

 two. The metathorax possibly reaches the mid-dorsal line 

 in the groove between the post-scutellum and the first 

 abdominal segment. The ventral surface of the meta- 

 thorax is both short and narrow ; it is largely occupied 

 by the insertion, close together, of the two hind legs. 



Proof of the boundaries of the segments is in most 

 places easily obtained by thin sections, though now and 

 then the determination is difficult. The apodemes, the 

 muscular intersections, and the intrinsic muscles of the 

 metathorax furnish the chief evidence. 



Legs. The legs' are long and 



slender. The fore pair, which 

 are longer than the others, 

 are usually raised in the air 

 like feelers, when the insect 

 is at rest. The last joint of 

 the tarsus of each leg bears 

 a pair of claws and a large, 

 bifid empodium, which acts 

 as an adhesive disc. 



Wings. The wings do not extend 



beyond the sixth abdominal 

 segment ; they are furnished 

 with two small accessory 



lobes close to the root. When at rest, the wings cover 

 the back and slope away on either side. The venation 

 is fully described in systematic books. 



Abdomen. The abdomeu is long and slender, especially in the 

 male, and consists of nine segments, the hindmost being 

 modified to form the reproductive armature. 



In the female fly the seventh abdominal segment is 

 normal (fig. 75), both the dorsal (tergum) and venti-al 

 plate (sternum) being well developed. The eighth seg- 

 ment shows a semi-lunar tergum and a pair of ventral 



Fig. 75 — Last abdominal segments 

 (vii, viii, ix) of female fly, ventral 

 view, sc, sclerite. go, genital orifice. 

 (7(70, outlet of gluten-gland, v, valve. 



