260 EVENINGS AT THE MICROSCOPE 



are expanded, a curious little organ, consisting of a couple 

 of fleshy tubes, the one sheathed in telescopic fashion 

 within the other, and bearing at its tip a pencil of 

 bristles, which can in turn be sheathed. This organ 

 doubtless represents the united antennae of Insects. 



But, you ask, what is that much more conspicuous 

 organ that is alternately thrust out and drawn back at 

 the bottom of the shell, and that is so nimbly whisked 

 about in all directions, looking, with its numberless trans- 

 verse wrinkles, and its little fingers at the tip, so like an 

 elephant's trunk in miniature? This is the creature's 

 foot; the only one he has; and as I said the little tubu- 

 lar telescope represents the two antennae fused into one, 

 so we must consider that this flexible member represents 

 all the six pairs of an Insect's legs united, or perhaps, 

 more philosophically, one of the pairs, the rest being ob- 

 solete. It must not be considered as a tail, not only from 

 its function, which is decidedly that of locomotion, but 

 also from its position on the ventral side of the intestinal 

 orifice. It is a curious organ, capable of great elongation 

 or, at the will of the animal, of entire retraction within 

 the abdomen; and this in an instant: while, as you ob- 

 served, it is flung about, and dashed from side to side, 

 and bent hither and thither with a sort of insane energy. 

 The means by which these movements are performed, you 

 may easily discern in several pairs of muscular bands 

 which run throughout its whole length, their upper in- 

 sertions being placed high up on the interior of the shell, 

 where, during contraction, you may see them swollen into 

 thick bulbs. 



The foot terminates in two short conical fingers or 

 toes, which can be drawn in or extended, widely sepa- 



