NO. 9 MUSCULATURE OF THE BLUE CRAB — COCHRAN 33 



700. Musculus adductor exopoditis III pedis maxillaris (fig. ii). — 

 This slender but strong muscle originates in the extreme distal anterior 

 part of the protopodite and runs inward to its insertion on a short, hard 

 projection of the inner proximal border of the exopodite, which is 

 pulled strongly toward the midline by the contraction of the muscle. 

 The crayfish does not appear to have this muscle. 



loi. Musculus abductor exopoditis III pedis maxillaris (fig. ii). — 

 This is a short, loosely-knit muscle arising ventrally on the median 

 border of the protopodite and running obliquely outward and forward 

 to its insertion on the heavy membrane attached to the ventral proxi- 

 mal wall of the exopodite. It moves the exopodite away from the 

 center and slightly outward. 



102. Musculus abductor flagelli III pedis maxillaris (fig. ii). — • 

 This strong muscle originates in two places on the proximal part of 

 the exopodite. The two sections soon unite, and the muscle is inserted 

 by a tendon on the outer proximal edge of the greatly enlarged first 

 segment of the flagellum, which is moved strongly upward and out- 

 ward by its action. 



loj. Musculus tlagcllaris exopoditis III pedis maxillaris (fig. ii). — 

 Originating on the proximal wall of the enlarged first segment of the 

 flagellum, this muscle goes almost to the tip of the flagellum, giving 

 off fibers to each annulus, and thus insuring freedom of motion to the 

 flagellum. 



104. Musculus flexor meropoditis III pedis maxillaris (fig. 1 1 ) . — 

 This muscle arises in numerous groups of fibers on both dorsal and 

 ventral walls of the ischiopodite. These fibers all join a tendon before 

 their final insertion on the inner proximal edge of the meropodite, 

 which is strongly pulled down by their action. There is apparently no 

 extensor muscle, the tension of the joint itself Ijeing sufiicient to bring 

 the meropodite back into position after its contraction by the flexor. 



105. Musculus extensor carpopoditis III pedis maxillaris (fig. 

 11). — This very slender and weak muscle originates midway on the 

 walls of the meropodite and is inserted on the outer proximal edge of 

 the carpopodite, which it pulls upward rather weakly. 



106. Musculus Hexor carpopoditis III pedis maxillaris (fig. ii). — 

 As might be expected from the condition in the preceding segment, 

 this muscle, which causes the bending toward the center, is very well 

 developed. It originates widely on the proximal margin of the mero- 

 podite and narrows to its tendinous insertion on the inner proximal 

 margin of the carpopodite. 



lOJ. Musculus flexor propoditis III pedis maxillaris (fig. ii). — 

 This muscle is similar to the flexor in the preceding segment in size 



