156 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D. Ser. 



The sperm-ducts are separate to the very point where 

 they enter the prostate glands. The prostates are confined 

 to one somite. They are very nearly straight, with the top 

 slightly bent over. They consist of two distinct parts, of 

 which the lower is narrower and strongly muscular. The 

 larger, glandular part is club-shaped, the inner or distal 

 part being the thickest. The sperm-ducts enter the muscu- 

 lar part at a point situated half-way between the body-wall 

 and the glandular part of the prostate. The glandular cells 

 are not arranged in two distinct layers; there are, however, 

 two kinds of glandular cells. The inner layer, consisting 

 of the narrowest cells, projects everywhere into the outer 

 layer, making the boundary between the two layers very 

 indistinct. 



The ne^hridia commence in somite II, but the body of 

 the first nephridium is situated mainly in III. Each 

 nephridium is furnished with a large terminal vesicle which 

 opens directly through the body-wall. There is no urinary 

 bladder, nor is the exterior pore furnished with large 

 sphincter cells, as in Microscolex elegans (Eisen 16). At 

 the point in the clitellum where the vesicle opens into the 

 pore, the clitellar cells suddenly narrow down, thus allow- 

 ing the vesicle to connect directly with the pore. The 

 nephropores are slightly ventral and anterior to setae c. 



Microscolex parvus, sp. nov. 



Plate XIV, Figs. 183, 184. 



Definition. — Length 35-45 mm., width i-i>^ mm. Somites 85. Pro- 

 stomium does not encroach on somite I. The ventral part o\\ somite I is half 

 as wide as its dorsal part; the somite is narrower than somite II. Dorsal 

 pores begin about VIII-IX, a very large one between XIII/XIV. Setae pos- 

 terior as well as anterior to the male pore converging towards that pore. 

 Penial setae sigmoid at apex. Spermiducal pores in XVII. Oviducal pores 

 separate, in line with setae I. Spermathecal pores in line with setae I, in 

 VIII/IX. Spermatheca with two diverticles. Testes, two pairs in X and XI. 

 Sperm-sacs small, racemose, in XI and XII. A small ovisac in XIV. Giz- 

 zard very rudimentary. Sacculated intestine commences in XVI. Sperm- 

 ducts open into the prostate. Muscular part of the prostate half as long again 

 as the glandular part. Color very pale flesh with pale, yellowish clitellum. 



