224 



SLUGS, FLUKES, EELWORMS, ETC. 



One of the chief characteristics of this class is that 

 the head and fore body (thorax) are ahiiost always- 

 joined or " fused" into one piece, known as the cephalo- 

 ihorax. In the Spiders the abdomen is joined to this 

 cephalo-tliorax by a short stalk, something in the same 

 manner as the abdomen of a Wasp is joined to the 

 fore body ; but in the Acarina, or Mites (with which 

 we have much more to do agriculturally), this is not 

 so; the head, thorax, and abdomen are fused, or joined 



Fig. 161. — Tyroc^lyplms longior (from fig. by Fumoze and Robin) : 

 claw and sucker, right-hand side (from ^Murray's ' Aptera') ; claw and 

 sucker on left-hand side, figured by Ed. from life : all magnified. 

 Nat. length rather more than half the 25th of an inch. 



into one continuous mass (see Fig. 161). As a rule, all 

 Mites when mature have four pairs of legs, excepting 

 the " Gall Mites," or Pliytopti, which have only two 

 pairs. These Pln/topti hatch out of the egg (as they 

 continue) with two pairs, but usually the young of the 

 Acarina are stated to hatch with only three pairs of 

 legs. 



The Mites are much too various in their habits and 

 structural details to allow of entering on these points 

 here. 



The "Red Spider" {Tetntinjclitis /(.7rt?-/»s), though 

 hardly large enough to be seen with the naked eye, is 



