INTERNAL ANATOMY. 123 



passes on each side of the supra-oesophageal ganglion 

 (PL 0, fig. 3). 



The Muscles which Shorten the Body. 



Nalepa says that in Garpoglyplms four longitudinal 

 muscle-bands arise from what he calls the shoulder- 

 notch on each side of the body ; pass close to the outer 

 wall of the abdomen, and are inserted by broad tendons 

 into the side of the body, about over the third coxa. 

 He says that the contraction of these eight muscles 

 must shorten the long axis of the body. 



The Muscles of the Alimentary Canal, 



The principal of these muscles are the pharyngeal, 

 which have already been fully treated of in connection 

 with that organ. The next in importance are the 

 divaricator muscles of the anus (PL C, fig. 2, mda) 9 of 

 which several bundles are inserted into the edge of the 

 anal opening ; they arise from the cuticle of the body, 

 and pass on both sides of the rectum. 



The Muscles of the Genital System. 



Some of the more interesting of these muscles will 

 be found referred to in the description of the repro- 

 ductive organs (pages 90 95, etc.). 



The Muscles of the Legs (PL C, figs. 3, 6, 7). 



These may be conveniently classed in two divisions, 

 viz. (1) those which arise in the body, and almost all 

 serve to move the entire leg; (2) those which arise 

 within the leg itself, and serve to move the respective 

 joints, or the claw. The first of these groups contains 

 some of the largest muscles of the body ; they are 

 naturally powerful, as they have the whole leg to move, 

 and many of the creatures are rapid ; they are mostly 

 inserted into the proximal edge of the coxa, although 



