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with a thin chitinous membrane. The cavity measures 

 •1 mm. by *01 mm. 



The cells forming the walls of the pharynx have very 

 distinct cell-walls; the nuclei are small, oblong, and stain 

 very deeply with hsematoxylin ; they measure *007 mm. 

 by *004 mm. Besides the lateral and dorsal muscles 

 attached to this part of the alimentary canal, described by 

 Laurie, I must draw attention to another set of muscles 

 connected with the pharynx. This set is a ring-muscle, 

 which runs round the pharynx; it evidently acts as the 

 antagonist of the lateral and dorsal muscles, and serves 

 to close the cavity when it has been distracted by the 

 other muscles. 



The pharynx goes over into the oesophagus, when it 

 enters the brain-mass. Its hollow is now Y-shaped. The 

 cells forming its walls are similar to those of the pharynx. 

 A distinct cuticle is still to be seen. It is no longer 

 enclosed in a ring-muscle, but is only covered with 

 connective tissue. After having passed through the brain, 

 the alimentary canal again changes its character and 

 becomes muscular once more. Its cavity is much wider 

 here and is X-shaped in transversal sections. The cells 

 forming this part much resemble those of the parts 

 already described. 



The musculature of the muscle-stomach can be divided 

 into two systems, similar to those of the pharynx. The 

 first of these consists of radial muscles, the longest of 

 which runs dorsally towards the carapace; the two others 

 are much shorter, and insert laterally in a cartilage, 

 which also serves to support the coxal gland. 



The other system again consists of a ring-muscle, 

 which is much stronger than that in the region of the 

 mouth. 



As yet the muscles are all smooth, in the adult they 

 are striated. The dorsal and lateral muscles pierce the 

 ring-muscle and insert in the walls of the stomach it self. 



The alimentary canal has a break in its continuity, 

 just behind the muscle-stomach; we next meet with it in 

 the abdomen. 



