CONTRIBUTIONS TO THE ANATOMY OF THE HIRUDINEA. 43? 



is not a permanent organ, but a temporary chamber, necessarily 

 formed when the proboscis is retracted. 



The mouth (see adjoining woodcut) m. is situated at the 

 extremity of the proboscis, c, with its muscular walls, d, these 

 latter being continuous with the walls of the oesophagus, o?. 

 The epidermis of the body is directly continuous with the 

 somewhat modified layer of flattened cells covering the mem- 

 brane, a, which becomes attached to the proboscidial wall at 

 /. (see figs. 21, 22, ep.). The salivary glands, gl. sal., send 

 their ducts, d., forward to enter the base of the proboscis, 

 and when this latter is retracted the ducts become more or 

 less coiled. 



gl. sal. 



Pig. 1.— Diagram of the proboscis of Clepsine. A. Retracted. B. Pro- 

 tracted, m, mouth ; c, wall of proboscis ; h, aperture of proboscidial 

 cbamber ; a, wall of the same; y^ point where the wall of the chamber is 

 reflected ou to the wall of the proboscis ; c, esophagus ; gl. sal., salivary 

 glands (three pairs only represented) ; d, salivary ducts. 



We may now proceed to examine the structure of the wall 



