ARACHNIDA. XIPHOSURA 



339 



prosoma or cephalothorax (fig. 144 A) and an abdomen 

 (B) formed of the mesosoma and metasoma fused together. 

 At the end of the abdomen is a long, movable tail- 

 spine (C). 



Fig. 145. Limulus polyphemus, Recent. Dorsal view. 1, carapace 

 covering prosorna (cephalothorax) ; 2, abdominal shield ; 3, tail- 

 spine ; 4, median eye ; 5, lateral eye. (From Shipley and MacBride.) 



22—2 



