184 THE HISTORY OF CREATION, 



account of their delicate skill in weaving, the union of the 

 joints of the trunk, or metamera, goes so far, that the trunk 

 now consists of only two pieces, of a head-breast (cephalo- 

 thorax) with jaws, feelers, and four pairs of legs, and of a 

 hinder body without appendages, where the spinning warts 

 are placed. In Mites (Aearida), which have probably arisen 

 by degeneration (especially by parasitism) out of a lateral 

 branch of Spuming Spiders, even these two trunk pieces 

 have become united and now form an unsegmented mass. 



The class of Scolopendria, Myriapoda, or Centipedes, the 

 smallest and poorest in forms of the four classes of 

 Arthropoda, is characterized by a very elongated body, 

 like that of a segmented Ringed worm, and often possesses 

 more than a hundred pairs of legs. But these animals 

 also originally developed out of a six-legged form of Trache- 

 ata, as is distinctly proved by the individual development 

 of the millipede in the egg. Their embryos have at fost 

 only three pairs of legs, like genuine insects, and only 

 at a later period do the posterior pairs of legs bud, one by 

 one, from the growing rings of the hinder body. Of the 

 two orders of Centipedes (which in our country live under 

 barks of trees, in moss, etc.) the round, double-footed ones 

 (Diplopoda) probably did not develop untd a later period 

 out of the older flat, single-footed ones (Chilopoda), by 

 successive pairs of rings of the body uniting together. 

 Fossil remains of the Chilopoda are first met with in the 

 Jura period. 



The thu'd and last class of the Arthropoda breathing 

 through trachese, is that of the Flies, or Insects, in the narrow 

 sense of the word (Insecta, or Hexapoda), the largest of all 



