92 



Hind -gut (PL V, fig. 34, h. g.) 



The hind-gut or intestine is a long narrow tube 

 extending from the posterior end of the mid-gut to the 

 anus which opens on the ventral surface of the telson. 

 Near to the mid-gut it passes below the median bridge- 

 like portion of the reproductive organs ; passing further 

 back it runs beneath the pericardium, and a short distance 

 behind the latter it enters the abdomen, along which it 

 pursues a straight course. Just before entering the 

 abdomen the hind-gut gives off from its right side a long 

 coiled tube the hind-gut caecum (fig. 34, i. caec.}. 



The caecum lies above the hind-gut, and the coils, 

 which are packed very closely together, extend into the 

 first segment of the abdomen. 



The hind-gut has very pronounced columnar 

 epithelium (PL X, fig. 62). This is lined by a thin 

 chitinous layer, consisting as in the fore-gut of an 

 outer cuticle, and a layer longitudinally striated which 

 appears to be continuous at the anus with the pigment 

 layer of the exoskeleton. The epithelium rests upon a 

 basement membrane outside of which are thin layers of 

 circular and longitudinal muscles. 



In the walls of the hind-gut immediately behind the 

 mid-gut there are closely packed glands very similar in 

 structure to those present in the walls of the oesophagus. 



There are also glands, having a similar structure to 

 the above, present in the walls of the hind-gut in the 

 abdominal region. They are not closely packed (fig. 62). 



DIGESTIVE GLAND. 



. The digestive gland (" liver," " hepato-pancreas ") 

 (PI. V, figs. 34, 37, 38, 39) is a large yellowish-brown* 



* This colour is due to lipochrome. (Miss Newbigin, Journ. 

 Physiol., Vol. XXI., p. 237, 1897.) 



