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take always their way along a muscular fibre, as is repre- 

 seuteJ iu figs. 8 and 10 (kb) : tbey open between the epitbelium- 

 cells witb a small orifice. The number of these glandtlucts is very 

 large; they are found along the whole side of the jaw and it 

 is remarkable they are not described as yet by any author on 

 Hirudiuea. 



The epithelium of the jaw consists of one layer of cells , which 

 are for the greater part more or less cubic. In colouring the 

 sections with naematoxyline , the sharply contoured oval nuclei 

 with their nucleoli contrast with the feebly stained protoplasma, 

 which is somewhat granular (fig. 10 e). 



In approaching the sharp convex edge of the jaw the epithe- 

 liumcells grow higher and especially there, where the cuticula 

 is thickest the cells have assumed some particularities (see fig. 

 3 and 4). Here the nuclei of the cells are difficult to be stained 

 and only after having carefully studied a great many preparati- 

 ons , I became couvinced that there was reaily an epithelium 

 present. The cells are very much elongated aud do not touch 

 each other, but small spaces are left between them. 



It must however be remarked that these spaces might be cau- 

 sed by shrivelling. In fact the cells are so much elongated, that 

 it is difficult to decide whether a cell is a muscularfibre or an 

 epitheliumcell ; especially because the nuclei of the epithelium 

 cells do not form a regular layer. 



The epithelium is covered by the cuticula, which at the con- 

 vex edge of the jaw grows much thicker. 



In my figures 3, 4 and 11 this thickening of the cuticula is 

 represented and the change of the epitheliumcells is demonstra- 

 ted at the same time. The thickening of the cuticula has gene- 

 rally the same shape in the Hirudinea; the greatest difference 

 Hirudo medicinalis aud Aulastomum gulo show, as is to be seen 

 in my figures 3 and 9. 



On the very edge of the jaw the cuticulae from both sides do 

 not quite touch, but leave a fissure, which at regular intervals 

 is obstructed by the teeth. The products of the salivary glands is 



