BEETLES THAT "BLUFF" 231 



old naturalists that the dancing May-fly is a sort of balloon, 

 but they were not acquainted with the exact mode of 

 inflation. Palmen says that in addition to the valve-like 

 arrangements we have described, the entry into the canal 

 is controlled by a circular muscle with which are con- 

 nected radiating muscles attached to the walls of the 

 head. The canal thus strangely transformed performs 

 the functions of a balloon, and at the same time aids the 

 functions of the reproductive organs. 



Where vast numbers of individuals set out simul- 

 taneously to achieve their nuptials there would seem 

 to be no need for special devices on the part of either 

 sex to call attention to their whereabouts. Nevertheless, 

 it is highly probable that the female exhales some dis- 

 tinctive odour ; otherwise, having regard to the fact that 

 she is overwhelmingly outnumbered by suitors, her dis- 

 covery in such a crowd would be impossible, and it is of 

 mal importance that no time should be lost in effecting 

 conjugation, for the time for its accomplishment is 

 perilously short. But there is another possible means of 

 discrimination — the males may distinguish the females by 

 the very different appearance of the head in the latter. 

 At any rate, this may be true of some species wherein 

 the males have no less than seven eyes, and these of three 

 different kinds 1 The compound eyes, characteristic of 

 insects, are, in these, divided, one half being set upon the 

 summit of a pillar raised high above the level of the head, 

 the other part remaining in its normal place at the side 

 of the head ; and in front of these, on what may be called 

 the forehead, are three separate simple eyes, or " ocelli." 

 A reference to Plate 32, Fig. 3, will make this clear. 



That the history of the later life of the May-fly is 

 remarkable no one will deny : in many respects it is 



