i6 Charles GELDERD 



This cavity is readily seen from thc dorsal aspect of the living animal, 

 lying close behind the eyes, and is somewhat green in colour on account of 

 the food it contains. It is oval in form. 



A pair of strong chitinous plates armed with tceth, hairs and spines 

 of varions kinds, are inserted at each side of the cavity, just above the 

 entry of the œsophagus. They run backwards towards the posterior part 

 of the chamber, fig. l, S. 



In carefully putting aside thèse plates by means of needles, a second 

 cavity is seen, the entry into which is guarded by chitinous eminences 

 bristling with teeth and hairs. 



This posterior cavity is distinctly separated from the anterior one, 

 ressembling what we find in the Decapoda. A narrow passage communi- 

 cates between the two through which the food passes, fig. i, Py. We may 

 mention hère, that the séparation is not so marked in the Edriophthalmia. 



In opening carefully the posterior cavity, we encounter a pair of latéral 

 plates concave in form, running from the floor of the cavity, and bridging 

 over an unpaired médian eminence. 



The whole stomach cavity with the œsophagus is covered with a caticle. 



The plates are moved by appropriate muscles. 



A pair of diverticula open into the posterior part of the second cham- 

 ber, on its ventral surface. Thèse are the corn mon canals of the digestive 

 glands, which hâve a bilatéral symmetry, consisting of five pairs of tubes. 

 The two upper tubes are short, the three lower are very long and occupy a 

 large portion of the thoracic cavity, fig. l, gl. 



The posterior cavity opens into the intestine, fig. i, /, which is a thin 

 tube without convolutions. Leaving the stomach, it describes a curve, 

 running down between the tubes of the digestive gland. Towards the 

 extremity of the thorax it rises again and passes above the muscular masses 

 of the pleon. In this région it is readily seen with the naked eye, near the 

 external dorsal integument, as a dark Une, when it is full of alimentary 

 matter. 



The intestine opens on the last segment of the body, below the telson. 

 We refer the reader to fig. 2, which is a diagrarn showing the divisions of 

 thc stomach, the relations between the hve principal pièces and their 

 situation in thc two chambers, from the dorsal aspect. 



AB marks the extcnt of the anterior chamber. 

 BC marks the extent of the posterior chamber. 



