THE FIRST AIR-BREATHERS. 



145 



Carnivorous Myriapods, however, or Centipedes proper, a 

 higher and essentially distinct type, are not known until much 

 more recent t. ^es. 



The insects of the Carboniferous as yet known, belong to 

 three out of the ten or more orders into which (he class is 

 divided. One of these is represented by a number of species 

 of Cockroach, another by May-flies and a Dragon-fly, and 

 another by some weevil -like Beetles. The Cockroach is cha- 

 racterised by Huxley as one of the " oldest, least modified. 



F.w. 126. — Millepedes. From the C^ al-formation. 



rt. XyloHus sigillnrife (Dawson). /', Architilus xyloHoidcs (Scudder), Anterior 

 segmtn's. iinlarged. c, X./arctus (Scudder). Caudal portion. Enlarged. 



and in manyAvays most instructive forms of insects;" and both 

 he and Rolleston take its anatomy as typical of that of the 

 class. That these creatures should have abounded in the 

 Coal-period we need not wonder, when we consider the habits 

 of those that infest our houses, and when we further bear 

 in mind the number of species, some of them two inches in 

 length, that exist in tropical climates. So many species ot 

 this family have been found in the Coal-formation on both 

 sides of the Atlantic,^ that we may fairly regard them as con- 

 stituting one of its most characteristic features, and as probably 



^ About fifty in all, as I learn from Mr., Scudder. 



