^02 /• PERCY MOORE. [Vol. X. 



delicate one in the spermatheca. The everted atrial cuticle 

 consists of a bulbous enlargement which belongs to the bursa, 

 and a slender tubular portion which lines the penis. 



The epidermis consists of ordinary epithelial cells, of non- 

 nucleate protoplasm, and of gland cells, which are present in 

 great number and variety. The epidermis proper presents 

 little modification. The cellular elements are arranged with 

 relation to the circular muscle fibres, which encircle the body 

 walls at regular intervals and are so deeply imbedded in the 

 epidermis that they are frequently almost in contact with the 

 cuticle, only a thin layer of protoplasm (less than the diameter 

 of a nucleus in thickness) separating them. Between these 

 muscle fibres the cells are arranged in zones, which are still 

 further broken up into groups by communicating branches 

 which pass between adjacent fibres (Fig. 3). The epidermis 

 may be described as made up of small irregular groups of cells 

 united by an external sheet of non-nucleated protoplasm ; the 

 cells lie between the muscle fibres, the non-nucleated proto- 

 plasm extends over them (Fig, 2). The entire external stratum 

 of the epidermis exhibits a fine vertical striation, doubtless 

 connected with cuticle secretion. (Fig. 2, si) Small spaces 

 {s), extending from intercellular spaces of the cellular zones, 

 are occasionally seen in the non-cellular regions ; and dark 

 lines, d, which I am unable to account for, are more frequent. 

 The cells are cubical and possess cell walls which are well 

 marked internally, but obscure peripherally in the striated 

 layer. The nuclei are large and deeply staining ; and possess 

 one or usually several nucleoli. Among the cells the trans- 

 parent ductules of unicellular glands wind their irregular or 

 spiral courses to the surface. In thickness the epidermis varies 

 from an average of .009 mm. in the non-cellular region to .018 

 mm. in the cellular. 



Anterior to the jaws there is no modification of the oral 

 epithelium, but within the pharynx it undergoes a marked 

 change, owing to the encroachment of the radial muscles, 

 which penetrate between the cells almost, if not quite (in part) 

 to the cuticle (Figs. 9 and 11, ep and nn). Between the 

 branching inner ends of these muscle cells the pharyngeal 



