PHYLUM ARTHROPOD A 



261 



ing by gills, in which the body consists of two regions, the 

 cephalothorax and the abdomen. The former is covered 



FIG. 157. Ventral view of Limulus. i-b, appendages of cephalothorax;' atd, 

 abdomen; ceph, cephalothorax; operc, operculum, behind which are seen the 

 series of abdominal appendages; tels, caudal spine or telson. (From Packard, 

 after Kingsley.) 



over by a broad shield or carapace, bearing two large com- 

 pound and two smaller, simple eyes. The segments of the 



