474 ^^- ^- MOORE. [Vol. X. 



The anus is terminal, the anal somite being a little longer 

 than the somites immediately preceding. 



In the anterior region the cross-section is nearly circular, 

 but behind the clitellum the body is more rectangular, in the 

 living worm being almost square, with setae borne upon the 

 angles. The setae are in four couples upon every somite, ex- 

 cept the first, where they are wanting. They are /-shaped, and 

 are nowhere modified, except to become less curved in the 

 clitellum. The two setae of the dorsal couple are closer to- 

 gether than those of the ventral couple. They are arranged 

 according to the formulae i — i>2 — 3=4 — 4 and i — 2 < 

 3—4. Posteriorly, the distance between couples is more 

 nearly equal. The nephridiopores open near the ventral couple 

 of setae, and commence in somite IV. Dorsal pores are 

 present, the first lying in furrow 5-6 and opening, internally, 

 into the somite behind. There are, usually, several evident in 

 the clitellum, and often the full number corresponding to the 

 six somites of that region may be demonstrated. 



In sexually mature individuals the body is much swollen in 

 somites XIV, XV, and XVI, each ventro-lateral region bearing 

 a somewhat nipple-shaped protuberance, whitish in color. 

 These protuberances are due, partially, to the development of 

 hypodermal clitellar tissue in this region, but principally to 

 the great development of the prostates. The external orifices 

 of these glands, the male genital-pores, are situated latero- 

 ventrally upon the posterior portion of somite XV, close to 

 furrow 15-16. The aperture is slit-like, and is surrounded 

 by a lustreless area, which makes its position very conspic- 

 uous. 



The regularity of the segmentation is somewhat interrupted 

 and disarranged in this region, the intersegmental furrow 

 15-16 being evident only dorsally, and in the middle region 

 ventrally; in the ventro-lateral region it is almost obliterated, 

 but may still be demonstrated in sections. Furrow 14-15 is 

 curved forwards, and 16-17 backwards around the base of the 

 prostatic prominence. Upon somite XIV, at the summit of 

 another, but much smaller papilla, is the oviducal pore, an 

 oblique, slit-like aperture near furrow 14-15, and internal to 



