94 METAMORPHOSES OF MAN 



CHAPTER X. 



METAMORPHOSES OF MYRIAPODS, CRUSTACEA, AND 



ANNELIDS. 



We shall now return to the invertebrata. The sub- 

 kingdom Annulosa contains, besides the insects, the 

 Myriapoda or Centipedes (Scolopendra lulus, &c), 

 Arachnida (spiders and scorpions), and Crustacea 

 (crabs, crayfish, wood-lice, &c). Of these three 

 classes, the second undergoes no metamorphosis ; but 

 the first and third exhibit this phenomenon, and 

 though not as generally as insects, yet occasionally 

 with characters that we have not met with among the 

 latter. 



The Iulidas have been the most fully investigated of 

 all the Myriapoda which undergo metamorphoses ; and 

 among those who- have devoted attention to them we 

 may mention De Geer, Savi, Waga, and Gervais. 

 When in the adult condition, these animals are com- 

 posed of a series of segments placed end to end like 

 the beads in a chaplet, of which nearly every segment 

 is provided with two pairs of limbs. These limbs 

 vary in number from 140 to 200, according to the 

 species. When the lulus first leaves the egg, its body 

 is quite smooth and devoid of legs. After a short 

 time it becomes divided into a number of separate 

 segments, and three pairs of legs are, as it were, 

 pushed out. As the animal grows older and goes 



