8 ART. 4. — I. IKEDA ! 



numerous small chitinous granules of a yellow color are so arranged 

 as to form a ring surrounding the external aperture of the sub- 

 dermal gland (see Figs. 30 a and h). In the middle region of 

 the body proper, the papillae are quite flat, elliptical in form and 

 much larger than in the posterior region. The chitinous granules 

 of such papillae are much smaller than those referred to above. 

 In the introvert, the papillae are very slightly elevated (nearly 

 0.015 mm. in height) and so small that they might appropriately 

 be called tubular with " Mündungskörper " (Fig. 31). The 

 introvert carries about 60 ring-rows of hooks of a small size. 

 The hooks in a way alternate in position with the tubular 

 papillae, there being about five of the former between every two 

 of the latter. The hooks are 0.025 mm. high, light yellow in 

 color, and are provided with a sharp and strongly curved apical 

 tooth and 4-5 short accessory teeth (Fig. 32). The accessory 

 teeth gradually decrease in number in the hooks forming the 

 more posterior rings finally to disappear altogether. The tentacles 

 are filamentous and nearly always 8 in number, surrounding the 

 oral aperture. The eye-spots are seen as two small, brown specks 

 lying on the lateral corners of the ganglion. 



The longitudinal musculature of the body-wall is continuous. 

 Of the two pairs of the retractor muscles, which are all slender, 

 the ventral pair {ym, Fig. 33) originate at the middle of the 

 body proper, while the dorsal {dm) do so far more anteriorly. 

 The anus lies at a position nearly midway between the origins of 

 the two pairs of muscles. A feature peculiar to this species is 

 presented by the sexual organs (so;). These are narrow band-like 

 structures situated at a considerable distance behind the origin 

 of the ventral rétracter muscles. The dorsal vessel {dv) is very 

 short, extending posteriorly for only a few millimeters beyond 



