VI 



APPENDAGES OK I.IMULUS 





another across the mesial plane and forming the genital operculum, the 

 genital openings being situated on their posterior face. Appendages 

 IX-XIII are also plate-like structures very much like the 



FIG. 98. 



A King- crab (Limulus), female. B, ventral view. I, Chelicera ; II-VI, walking N^s ; 

 VII, chilarium ; VIII, genital operculum ; IX-XIII, respiratory appendages; a, anus ; t, telson.. 



culum, differing from it, however, in that each carries on its posterior 

 surface an arrangement of thin flat plates, lying over one another like 

 the leaves of a book (Fig. 101, A). These gill-books are the breathing 

 organs of the Limulus, each leaf containing blood and possessing a very 



