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LIMULUS 



1. Limulus, dorsal view. Cephalothorax ; abdomen; spines (six on each side) on margins of 

 abdomen ; telson ; the two compound eyes at the sides of the median region of the cephalothoracic 

 carapace ; the two simple eyes at the front end of the same region. 



2. Limulus, ventral view. Pediform legs on cephalothorax (six pairs), the last five with gnatho- 

 base ; spatulate digging processes on last leg ; genital operculum ; lamellar abdominal appendages (five 

 pairs) with gill books ; anus ; telson ; position of mouth. 



3. Casts of fossil forms Eurypterus and Prestwichia. 



