782 CLASS V. ARACHNIDA. 



first region. This bears four pairs of appendages usually called 

 (i) the mandibles, two- or three-jointed and often chelate ; 

 (ii) the palpi, three- to ten-jointed : either the mandibles or 

 the palpi may be absent in the adult or at some embryonic stage, 

 but they are always present sooner or later ; (iii) the ovigerous 



FIG. 508. Ammothea pycnogonoides (re'gne animal). Da prolongations of alimentary canal 



into the legs. 



legs, always present in both sexes ; they are usually ten- jointed 

 and in the male bear the eggs. The posterior part of the first 

 region bears two lateral processes at whose extremities (iv) the 

 first walking legs are articulated. The legs are eight-jointed 

 and end in a claw and in some cases two accessory claws. Be- 

 hind this first region come three free segments corresponding 

 with the sixth and seventh and eighth somites of the scheme 

 (p. 775), each bearing a pair of walking legs at the end of lateral 

 processes which stick out from the body. Between the last pair 

 of processes a tubercle projects which bears the anus at its end : 

 this is the rudimentary abdomen. 



Pantopods usually possess four eyes situated on a tubercle 

 borne dorsally on the first region. Even when the eyes are absent, 



