622 L. H. GOUGH. 



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 itself. 



The alimentary canal has a break in its continuity, just 

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

 abdomen. 



Through in-foldings of the coelom the yolk is divided into 

 several distinct masses. The walls of the midgut are in part 

 formed by the coelom. At its anterior end it is wide, open, 

 and funnel-shaped, and it tapers towards its posterior end. 

 It is everywhere filled with yolk. On the interior side of the 

 funnel formed by the coelom the entoderm cells have built up 

 an epithelium. This epithelium seems to be separated by a 

 membrane from the walls composing the coelom. 



The cells forming the lining of the midgut have 

 distinct cell-walls-; their nuclei stain lightly with hasma- 

 toxyliu ; they are perfectly round^ and measure "01 mm. 

 ill diameter. A micro-nucleus is often to be found in 

 them. 



