SEA-FISHERIES LABORATORY. 365 



and its origin is on the anterior wall of the latter. It 

 passes downward behind the anterior extensor, and is 

 inserted on an extremely long tendon which arises from 

 the joint immediately behind the tendon of the anterior 

 flexor (fig. 21, p. f. B., Text fig. 10, h.). 



The lesser posterior flexor is situated on the inner and 

 anterior region of the fourth pleural chamber. It passes 

 outward, and is inserted on a small tendon in front of the 

 posterior hinge (Text fig. 10, g.). 



The Meropodite has very little movement, and the 

 muscles are extremely small. 



The extensor is a small muscle arising from the 

 posterior wall of the ischium. It passes downward and 

 backward, and is inserted on a small tendon on the ventral 

 side of the meros (fig. 21, t. ex. M.). 



There does not appear to be a definite flexor muscle, 

 but when the extensor muscle relaxes, tiie weight of the 

 distal portion of the limb is sufficient to produce the small 

 amount of flexion necessary. 



Carpopodite. There is an anterior flexor and a 

 posterior extensor muscle. 



The extensor arises from the posterior walls of the 

 meros throughout its entire length. The insertion of 

 the muscle is on a long tendon situated near the dorsal 

 hinge of the carpos. This tendon lies in the dorsal part 

 of the meros and extends almost to the proximal end of 

 the latter {ex. C l ). 



The flexor has its origin on the anterior walls of the 

 meros. Its tendon is similar in size to that of the 

 extensor. It lies in the ventral region of the meros, and 

 arises from the antero-ventral border of the carpos (/. C. 1 ). 



Propodite. There is a posterior extensor and an 

 interior flexor muscle. 



The extensor arises from the posterior walls of the 



