278 MOTIONS OF INSECTS. 



est fictions of the imagination. Should a traveller tell 

 you that he had seen a quadruped whose legs were on 

 its back, you would immediately conclude that he was 

 playing upon your credulity, and had lost that regard 

 to truth which ought to distinguish the narratives of 

 persons of his description. What then will you say to 

 me, when I affirm, upon the evidence of two most unex- 

 ceptionable witnesses, Reaumur and De Geer, that there 

 are insects which exhibit this extraordinary structure ? 

 The grub of a little gall-fly, appearing to be Cynips 

 Quercus inferus of Linne which inhabits a ligneous gall 

 resembling a berry to be met with on the underside of 

 oak-leaves was found by the former to have on its back, 

 on the middle of each segment, a retractile fleshy protu- 

 berance that resembled strikingly the spurious legs of 

 some caterpillars. A little attention will convince any 

 one, argues Reaumur, that the legs of insects circum- 

 stanced like the one under consideration, if it has any, 

 should be on its back. For this grub inhabiting a 

 spherical cavity, in which it lies rolled up as it were in a 

 ring when it wants to move, will be enabled to do so, 

 in this hollow sphere, with much more facilit}', by means 

 of legs on the middle of its back, than if they were in 

 their ordinary situation a . So wisely has Providence or- 

 dered every thing. Another similar instance is recorded 

 by De Geer, which indeed had previously been noticed, 

 though cursorily, by the illustrious Frenchman 5 . There 

 is a little larva, he observes, to be found at all seasons 

 of the year, the depth of winter excepted, in stagnant 

 waters, which keeps its body always doubled as it were 



aReaum. iii. 496. t. xlv./. 3. 



'' Ibid. Mem. de tAcad. Roy. des Sciences de Paris t An. 1714. p. 203. 



