Thorax in winged Insects. 173 



which passes a Hgament which this author calls the funiculvs, and which 

 serves, as he correctly says, to support the abdomen. The two lateral 

 apertures are false, being formed above by the two horny lobes of the 

 interior of the horse-shoe, and below by the membrane which forms one 

 side of the passage' for the intestines from the thorax to the abdomen. 

 The aperture of the thorax which forms this passage is best seen by turn- 

 ing up the metathorax, when it will be observed to be terminated by a 

 lozenge-formed section laterally widest, having the trochlea in front, the 

 two sockets for the legs at the sides, and the passage for the intestines in 

 the middle. 



5. 'The paraptera are small trapezoidal pieces which intervene be- 

 tween the preescutum of the metathorax and the sockets of the under 

 wings. In general the paraptei-a belong to the pectus ; but as in our 

 insect they are situated above the wings, I have thouglit il best to describe 

 thenj in this place.* 



Of thb Pectus. 



'J "he order of Hymenoptera is in general so essentially flying that the 

 tergum of the whole thorax undergoes, as we have seen, a very great de- 

 velopement, which of course occasions the pectus to be very little deve- 

 loped as to size, except in Ants and other tribes which are essentially 

 walkers. This part of our investigation therefore will be proportionably 

 difficult, although I think the excellent principles of M, Audouin will 

 enable us to surmount the difficulty. 



1. Of the Pectus of the Prothorax. 



The pectus is diminished in size, as I have said, owing to the great de- 

 velopement of the mesothorax. But typically it ought to consist of six 

 pieces, viz. 



1. The sternum of the prothorax in Polistes is narrow, and I know 

 no better way of describing its shape than as resembling a sand glass 

 placed on an escutcheon.f According to Mr. Kirby's definition, the 



whole matter perfectly explained without the intervention of either wheels or 

 pullies. I have represented the postscutellum of Polistes in figures 5 and 7. 

 • Fig. 5, O. t f 'ff- 8, U, 



