28o 



OAK GALLS AND GALL INSECTS 



The meta-thorax is very small, though the pleural and sternal regions and 

 the meta-notal stigma are quite distinct. 



(5.) The median segment, though in reality the first abdominal segment, 

 form? in the Cynipina and other Hymenoptera, a fourth thoracic segment. 

 It is, as it were, separated from the abdomen by the petiole, and is often con- 

 founded with the meta-thorax. In reality the petiole is the second abdominal 

 segment. The stigma of the median segment may be larger, foveate or 

 reticulate. 



(6.) Lcfjs. Of moderate size. Trochanters bi-articulate. There are 

 either one or two spurs on the fore tibiae, and on the hind tibiae there are 

 two unequal spurs. The Meta-tarsiis is long and the tarsi are four-jointed. 



Cluws may be simple or^cleft. 



Patella seldom conspicuous. 



I 



Vk 



Aiuliieiis collaris (Htg.) Pertect msect, magnified. An example 

 of the Sub-Family Cynipina. 



(7.) The Abdomen varies much in form. It maybe slender or thick, long 

 or ovate. Sometimes it appears to be nearly sessile, which is due to the shape 

 of the patiole. 



According to Cameron there are seven abdominal segments, which 

 differ in length, especially the second and third, a point much used in 

 classification. The apical ventral segment may be ploughshare shaped The 

 number of segments in the abdomen differs with different authors according 

 to whether thev consider the medium segments or the petiole to be the first 

 abdominal segment. In reality the median segment is. If this latter view is 

 taken the abdomen consists of eight instead of seven segments, the varying 

 segments being the third and fourth. There are only six visible segments on 

 the ventral region of the female, and five in the male. 



The Ovipositor, which has been previously described, has its origin close to 

 the base of the abdomen. 



