( clxiii ) 



a pair of somewhat cone-shaped pads, below which is the 

 sedoeagal ring with its two pairs of tusk-like apophyses that 

 appear to be characteristic of the family; the sedoeagus is 

 very irregular in outline with a heavily armatured apex. 

 The sensory pads on the venter of the terminal abdominal 

 somite are rovmded and furnished with long strong hairs. 



The Hymenoptera have these organs developed an(J 

 specialised to a considerable extent; the late Edward Sanders 

 dealt with them in our Transactions as long ago as 1884, and 

 I only propose to refer to one or two types of the Aculeala 

 so that I may demonstrate the line of specialisation in Vespa 

 and in some of the Formicidae. 



Vespa germanica. 



The organs are developed almost entirely along the lateral 

 line; they are very ample, indeed so ample that they extend 

 on to the lower part of the dorsum and also on to the venter 

 of the female ; there are apophyses on each of these margins, 

 those on the dorsal edges being long, irregular, and thickly 

 haired; the sedoeagus is longish with a large basal area, the 

 apical half being a moderately broad tube with barbed apex. 



Vespa sylvestris 



is very similar to germanica, as we should expect, but is 

 simpler, whilst the lateral armature is different in shape; 

 the oedoeagus also is different in small particulars. 



Formica rufa, L., 



has the development also almost entirely along the lateral 

 line, as also have others of the group, it is, however, flat, not 

 curved, that is to say that the lateral plates are apparently 

 flat ; but to make up for the loss of power involved by being 

 unable to curve around the abdomen of the mate — as in Vespa 

 — the internal surface is supplied with strong hooks or saws 

 or both, so that the grasping capabilities must be great. 



Formica fusca, L., 



is very similar indeed to the preceding species, but the 

 internal hooks are different in shape, as also the lateral plates, 

 which are also smaller. 



