26 Charles GELDERD 



Their internai borders are armed with strong curved spines the points 

 of which meet in the médian line. 



They reach the same level as the summit of the médian pièce ^j. 



FiG. 19 shows very clearly the relations between the terminal pièces of 

 the p3doric chamber. 



At this Icvel they are ail detached from the wall of the cavity and the 

 beginning of the epithelium of the intestine is seen. 



Musculav System. 



The mouth, œsophagus and stomach are furnished with muscular 

 Systems to enable them to carry out their varions functions. 



We hâve already observed that the œsophagus possesses a séries of 

 circular muscle fibres. 



Other muscular bands of much greater strength connect the œsophagus 

 with the external integument of the animal in various points. 



A pair of such extrinsic muscles is seen in fig. 5, ind. 



The stomach is attached to the dorsal integument by strong bands of 

 muscle which run frôm a slight dépression behind the superior médian 

 pièce. They run in the form of curves and are attached some distance 

 back to the dorsal cuticle, fig. 3, m. 



A pair of longitudinal muscles run through the superior médian pièce, 



FIG. 6, 8. 



It is but to be expected that the stomach pièces will necessarily be 

 supplied with a complicated séries of muscles, considering the various 

 movements that they are called upon to perform. 



The cardiac chamber possesses a System of muscle fibres which almost 

 encircle it, running obliquely at the side of the plates 5i, and passing 

 beneath the ridge c. 



They are attached to the upper borders of the plate,?, fig. 4, 5, 6. 



On account of the oblique direction which they takc, our sections 

 show only the transverse section of the muscle bands ; they are seen lying 

 close to one another. 



The pyloric chamber possesses similar bands of circular muscles, 

 FIG. 15; those at the entrance to the pyloric chamber seem to be of greater 

 strength, fig. 7, 8. 



Other muscular Systems connect the stomach pièces with the external 

 integument. 



