298 DISEASES OF INSECTS. 
merobii, when they lay their eggs, know how to place 
them upon a kind of footstalk, so the parent Uropoda 
has the same power; and this pedicle appears to act the 
part of an umbilical chord, conveying nutriment to the 
foetus not from a placenta, but from the body of the in- 
sect to which it is attached; till having thus attained a 
certain maturity of growth and structure, it disengages 
itself and becomes locomotive. Many eggs of the aqua- 
tic Acarina (Hydrachna, &c.) are also furnished with a 
short pedicle by which they are fixed to Dytisci and 
other water insects. De Geer found some of this de- 
scription on the underside of the water-scorpion, so 
thickly set as to leave no void space: they were oval, of 
a very bright red, and of different sizes on different indi- 
viduals; whence it was evident that they grow when thus 
fixed: when hatched or released—for perhaps they may 
be regarded as foetuses in their amnios rather than eggs 
—they cease to be parasitical. Let us admire on this 
occasion, (piously observes this great Entomologist, ) the 
different and infinitely varied means by which the Au- 
rHor of Nature has endowed animals, particularly in- 
sects, for their propagation and preservation: for it is a 
most extraordinary sight to see eges grow, and pump as 
it were their nutriment from the body of another living 
animal?. As these mites are fixed to the crust as well as 
its inosculations, they must have some means of forcing 
their nutriment through its pores. 
Another insect, remarkable for its resemblance in some 
respects to the scorpion—called in this country the book- 
crab (Chelifer cancrordes), from its being sometimes found 
“ De Geer vii. 144—, 
