THE ALIMENTARY CANAL AND ITS APPENDAGES. 



127 



The anus of the Cockroach opens beneath the tenth tergum, 

 and between two " podical ' plates. Anal glands, such as 

 occur in some Beetles, have not been discovered in Cockroaches. 



Appendages. The Salivary Glands. 



The three principal appendages of the alimentary canal of 

 the Cockroach are outgrowths of the three primary divisions of 

 the digestive tube ; the salivary glands are diverticula of the 

 stomodseum, the caecal tubes of the mesenteron, and the Mal- 

 pighian tubules of the proctodseurn. 



Fig. 71. Salivary Glands and Receptacle, right side. The arrow marks the opening 

 of the common duct on the back of the lingua. A, side view of lingua ; B, front 



view of lingua. 



A large salivary gland and reservoir lie on each side of the 

 oesophagus and crop. The gland is a thin foliaceous mass about 

 J in. long, and composed of numerous acini, which are grouped 

 into two principal lobes. The efferent ducts form a trunk, 

 which receives a branch from a small accessory lobe, and then 



m 



unites with its fellow. The common glandular duct thus 



