ANATOMICAL STRUCTURE OF KERRIA. 309 



prostate is more than five times as long on the muscular 

 part. The muscular part of the anterior prostate is 

 also comparatively much narrower than the muscular 

 part of the posterior prostate. The glandular part of the 

 respective prostates is of much the same form. They 

 are thickest in the vicinity of the muscular part and taper 

 toward the inner free apex, which is narrow and pointed. 



Judging from Beddard's figure of Kerria halophila, the 

 prostates of those species resemble greatly those of our 

 present form. The muscular part is longer in the an- 

 terior prostate than in the posterior one, and the gland- 

 ular part of the prostate is widest close to the mus- 

 cular part just as in Kerria McDonald/, but they are 

 hardly tapering as much as in that species and the inner 

 apex is less pointed. 



The prostate pores are larger than the spermiducal 

 pores and can be seen without much difficulty, though 

 they are by no means plainly perceptible. 



Nephridia (figs. 4, 5 and 28). These organs resemble 

 those of Ocnerodrilus and especially those of Ocncro-. 

 drilus Beddardi. The anterior nephridia are devoid of 

 large peritoneal cells, while in those posterior of the 

 clitellum the upper part of the tubes are entirely hidden 

 by these cells. 



The five nephridia anterior to somite ix are small, 

 always devoid of peritoneal cells. The nephridia in ix 

 are much larger, furnished with some peritoneal cells, 

 those in x and xi are smaller. After these the nephridia 

 gradually increase in size, those in the extreme posterior 

 part of the body being always the largest and of equal 

 size. The peritoneal cells gradually increase in number 

 toward the last quarter of the body, but this increase is 

 quite irregular. In some specimens these cells are many, 

 almost filling the whole somite, in others they are few, 



•2d Ser , Vol. in. (23) April 15, 1893. 



