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fourth sternal muscle chamber, and arises from the fourth 

 thoracic sternum. Its course is outward, upward and 

 backward, and at its outer extremity it is inserted on a 

 broad tendon lying on the ventral side of the basi-ischium, 

 mid- way between the two hinges (fig. 21, a. f. B., Text 

 fig. 10, *.) 



c. 



V. 



FIG. 10. The proximal end of the chela, after all the soft tissues have 

 been removed. The tendons of the muscles moving the coxa and 

 basi-ischium are shown. (The upper side of the figure is dorsal, 

 and the right side is the anterior end.) 



Coxopodite. a. = dorsal hinge ; b. = ventral hinge ; c. = tendon of 

 flexor muscle ; d. = tendon of extensor muscle. 



Basi-ischium. e. = posterior extensor muscle ; /. = anterior extensor 

 muscle ; g. = lesser posterior flexor muscle ; h. = greater posterior 

 flexor muscle ; k. = anterior flexor muscle ; I. posterior hinge ; 

 m. = anterior hinge. 



The greater posterior flexor lies in the outer and 

 anterior portion of the fourth pleural muscle chamber, 



