MOTIONS OF INSECTS. 981 
of which has three long claws. ‘This animal has a ra- 
diated anus, and seems related to those flies that live in 
the nests of humble-bees?. 
Insects in the peculiarities of their structure, as we 
have seen in many instances, sometimes realize the wild- 
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 Linné—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. Vor this grub—inhabiting a 
spherical cavity, in which it lies rolled up as it were ina 
ring—when it wants to move, will be enabled to do so, 
in this hollow sphere, with much more facility, by means 
of legs on’ the middle of its back, than if they were in 
their ordinary situation>. So wisely has Providence or- 
dered every thing.— Another similar instance !s recorded 
4 De Geer, vi. 137. ¢. vill. f. 8, 9. > Reaum. iii, 496. ¢. xlv. fi 3. 
