NO. 9 MUSCULATURE OF THE BLUE CRAB COCHRAN 37 



anterior projection of the promotor of the fifth pereiopod, and gives 

 additional room for attachment to the numerous branches of muscles 

 governing the movements of the leg base. 



THE FIRST PEREIOPOD 



III a, b. MusckIus promotor a and h (figs. 12 A, 13 B).— The 

 anterior branch (a) originates upon a narrow, curved apodeme which 

 comes inward and forward from the floor of the gill chamber and 

 attaches itself laterally by a process to the sternum and medially to the 

 endosternite between the third and fourth thoracic segments. The 

 muscle passes outward and downward to its attachment on a heavy 

 membrane coming from the preaxial proximal border of the coxopo- 

 dite. The posterior branch {b) originates on the anterior border of the 

 intermediate endopleurite of this segment and ends upon a heavy ten- 

 don attached to the anterior border of the coxopodite and directly 

 behind the attachment of branch a. These two parts give a strong for- 

 ward pull to the basal part of the leg. 



112. Musculus remotor (fig. 12 C). This is the only unbranched 

 muscle controlling the leg base. It takes origin partly on the lateral 

 surface of the membrane enclosing the anterior promotor of the fifth 

 pereiopod behind 113 c and partly on the anterior part of the endo- 

 pleurite separating the fifth and sixth thoracic segments. It is inserted 



Fig. 12. — The pereiopods. 



A, B, C, the first pereiopod. 



14, musculus attractor epimerahs ; iiia-b, musculus promotor a-b; 112, mus- 

 culus remotor; ii3a-c, musculus levator a-c; ii40'-g, musculus depressor a-g; 

 115, musculus reductor meropoditis; 116, musculus abductor carpopoditis ; 117, 

 musculus adductor carpopoditis. 



D, E, F, the second pereiopod. 



I22a-d, musculus promotor a-d; 123, musculus remotor; I24a-d, musculus 

 levator a-d; I25a-e, musculus depressor a-e; 126, musculus reductor mero- 

 poditis; 127, musculus abductor carpopoditis; 128, musculus adductor carpo- 

 poditis. 



G, H, I, the third pereiopod. 



1330-9, musculus promotor a-g; 134, musculus remotor; I35a-c, musculus 

 levator a-c; I36a-e, musculus depressor a-c; 137, musculus reductor meropoditis; 

 13&, musculus abductor carpopoditis; 139, musculus adductor carpopoditis. 



Bs-Iscpd, basi-ischiopodite ; Cxpd, coxopodite. 



J, K, L, the fourth pereiopod. 



I44a-d, musculus promotor a-d; 145, musculus remotor ; I46a-h, musculus 

 levator a-b; I47a-d, musculus depressor a-d; 14S, musculus reductor mero- 

 poditis; 149, musculus abductor carpopoditis; 150, musculus adductor carpo- 

 poditis. 



M, N, O, the fifth pereiopod. 



I55a-c, musculus promotor a-c; I56a-b, musculus remotor a-b; I57a-c, mus- 

 culus levator a-c; isSa-j, musculus depressor a-j ; 139, musculus reductor 

 meropoditis ; 160, musculus abductor carpopoditis ; j6j, musculus adductor carpo- 

 poditis. 



