NO. 9 MUSCULATURE OF THE I5LUE CRAB COCHRAN 2."] 



7J a, b. Mitsculus attractor cpipoditis a and h J pedis niaxillaris 

 (fig. 9). — One branch of this muscle arises on the dorsal portion of 

 the paraphragm between the first and second thoracic segments, lying 

 directly below the first respiratory muscle of the second maxilla. It 

 passes outward and forward to its insertion on the outer dorsal proxi- 

 mal border of the epipodite, which it raises strongly, at the same time 

 causing it to move backward and inward. The second branch, larger 

 and more powerful than the first, passes under the first on its forward 

 and outward path to its insertion beneath it on the ventral proximal 

 border of the epipodite, which it brings strongly backward and 

 downward. 



/4. (Fig. 9). — This short muscle arises deeply within a cuplike 

 membrane beside the inner epistomal rim and is inserted at the base of 

 the first endite on the coxopodite. It is impracticable to give a 

 functional name to this muscle, although it undoubtedly controls the 

 coxopodite in some way. It might perform the duties of a levator, but 

 this can not be ascertained directly. 



y^. (Fig. 9). — This short but thick muscle arises on the mesal edge 

 of the same cuplike membrane as does the preceding muscle, and is 

 inserted deeply within the first endite of the coxopodite. It is not 

 possible to name it as to function, although it presumably causes what- 

 ever motion the first endite is capable of making. Its position is some- 

 what similar to that of the depressor in Pandalus and Astacus. 



/6. (Fig. 9) . — This short but heavy muscle arises on the lateral edge 

 of the same cuplike membrane which gives origin to the two preceding 

 muscles and is inserted beside and lateral to 74, where the first and 

 second endites come together. Again a functional name is not forth- 

 coming as no positive motion can be assigned to this particular muscle. 



21. Musculus adductor exopoditis I pedis maxillaris (fig. 9). — This 

 muscle originates on the posterior surface of the coxopodite just 

 lateral to the insertion of /6, and runs laterally to its insertion on the 

 outer anterior proximal border of the exopodite just above the ori- 

 gin of 78. It brings the exopodite, and with it the partly fused .endopo- 

 dite, away from the epipodite and toward the center. Berkeley men- 

 tions a well-developed abductor exopoditis in Pandalus, not present in 

 the blue crab. The endopodite of the blue crab has no muscles of its 

 own. 



y8. Muscidus abductor dagelli exopoditis I pedis maxillaris (fig. 

 9). — Arising in two places on the inner ventral proximal wall of the 

 exopodite, this powerful muscle unites and passes to its insertion on 

 the inner proximal edge of the enlarged first segment of the flagellum. 

 It causes a strong upward and outward movement in the flagellum. 



