HYMENOPTERA : STRUCTURE. 



375 



intended uses, is but a modification of the same instrument. 

 From the centre of the under- side of the abdomen, near its 

 extremity, arise two plates, each consisting of two joints, 

 sometimes valvular, and together forming a scabbard, some- 

 times more slender, and resembling palpi, and sometimes 



Bee's Sting. 



very long ; between these plates (fig. 1 and 2, as they exist 

 in the bee, under the form of two flattened plates, with a 

 pair of small terminal lobes) arise two other pieces, which 

 are very slender, serrated at the tip in the bees (fig. 3 and 5), 

 but much broader in the saw-flies, and transversely striated, 

 forming the saws with which these insects are provided : 

 moreover, these two pieces are received, in the bees, into a 

 canal (fig. 2 and 4), but in the saw-flies this gutter is broad, 



A, extremity of the abdomen of the Saw-fly, showing the two saws and their supports rf, 

 extended ; a, the terminal joint of the abdomen ; and b, the internal horny sheath. B, a 

 small portion of one of the aws, very highly magnified. 



