The AmmophilcB 245 



point attacked from the original segment. At 

 the hinder end in particular, the least touch 

 provokes wild contortions. There was only one 

 sting, therefore, and it was administered to the 

 fifth or sixth ring. 



What peculiarity then do these two segments 

 possess that one or other of them should be 

 the target of the assassin's weapon ? None 

 whatever in their organization ; but their 

 position is another matter. Leaving the Silky 

 Ammophila's Measuring-worms on one side, 

 I find that the prey of the others is organized 

 as follows, the head being counted as the first 

 segment : three pairs of real legs on the second, 

 third and fourth rings ; four pairs of mem- 

 branous legs on the seventh, eighth, ninth and 

 tenth rings ; lastly, a final pair of membranous 

 legs on the thirteenth and last ring, making in 

 all eight pairs of legs, of which the first seven 

 form two vigorous groups, one of three, the 

 other of four pairs. These two groups are 

 separated by two legless segments, which are 

 precisely the fifth and sixth. 



Now, in order to deprive the caterpillar of 

 its means of escape, to render it motionless, 

 will the Wasp drive her sting into each of the 

 eight rings provided with locomotory organs ? 

 Above all, will she take this superfluity of 

 precaution when the prey is quite weak and 



