EXTERNAL ANATOMY OF INSECTS. 701 



I shall enlarge a little upon it. You would be surprised, 

 and not without reason incredulous, were I seriously to 

 assert that these insects lift their weighty posteriors 

 by means of a rope and pulley; yet something like this 

 really does take place, though not with all in a manner 

 equally striking. The point of articulation in the insects 

 in question, except in Evania, is at the base of the meta- 

 thorax just above the posterior pair of legs: here you see 

 a small orifice, either insulated or connected by a narrow 

 opening with the larger one, when the abdomen is re- 

 moved, which in many instances, as in the common wasp, 

 is surmounted by another still smaller, through which, 

 if you examine it attentively, you will find there is trans- 

 mitted a fiat and sometimes broadish ligament or rather 

 tendon, in which the levator muscles of the abdomen, at- 

 tached by their other end to the metaphragm 3 , terminate: 

 another minute orifice above the base of the pedicle af- 

 fords a point of attachment to the tendon, so as to give 

 it prize upon the abdomen. Here the upper orifice in 

 the trunk is the pulley (t?*ochlea) b , the tendon is the 

 rope (funiculus)*', and the abdomen is the weight to be 

 lifted. When the muscles contract, the tendon, running 

 over the edge of the aperture, is pulled in, and the part 

 just named is elevated ; and when they are relaxed the 

 tendon is let out, and it falls. Some little variation in 

 the structure takes place in different tribes : thus, in the 



a It was omitted to be observed, when the supposed pneumatic 

 pouches in the genus Vespa were mentioned (see above, p. 585), that 

 they have also a very conspicuous metaphragm, as probably have 

 most Hymenoptera, to which the muscles that move the wings are 

 •attached. 



b Plate IX. Fig. 13. F' is the tendon, G' the aperture in the 

 abdomen C, and a, the aperture in the trunk B. 



