16 ART. 4. T. IKEDA : 



color, more deeply yellow in the middle portion of tlie body 

 proper. The greater part of the body-surface appears nearly 

 smooth to the naked eye, except on the introvert-basis which is 

 rough on account of the presence of tall papillie and prominent 

 chitinous folds. Under the microscope, it is seen that the ap- 

 parently smooth part of the surface is beset with skin-papillte 

 which vary much in shape and size in different portions of tlie 

 body. In the anterior region of the introvert, the papillae are 

 very small, transparent, oval bodies, measuring 0.025 mm. in 

 height and 0.014 mm. in basal diameter. From that region 

 posteriorly, they become somewhat larger and taller, but less 

 closely arranged, and in the middle parts of the introvert they 

 measure about 0.028 mm. in height and 0.02 mm. in maximum 

 breadth (Fig. 46). On the introvert-basis, the papilhe are rather 

 prominent, showing a club-like shape and measuring about 0.1 mm. 

 in height and 0.05 mm. in thickness in the broadest part. 

 They have a thick wall, are yellow in color and are perforated 

 by a narrow and likewise club-shaped canal which proximally 

 communicates by a small pore with the cavit}?^ of the subdermal 

 gland (Fig. 47). The minute external aperture on the apex 

 of the papilla can scarcely be brought into view. Intermixed 

 with the papillœ are present large, irregularly shaped thicken- 

 ings of the chitin (see Fig. 47) ; these appear finely granulated 

 and are of a deep brown color. In the anal region, the papillae 

 abruptly become short (0.04 mm. high) and exhibit a conical 

 form with a basal diameter of 0.046 mm. on an average. The 

 apex of such a papilla is occupied by a small mamelon-like 

 body which is pierced through by the papillary canal. Most 

 of these papilhe are situated amongst closely set, large and 

 irregular chitinous thickenings of coarsely granular appearance 



