ZooL.— Vol. II.] RISEN— OLIGOCHMTA. II9 



Septal formula: — 



V/VI; VI/VII; VII/VIII; VIII/IX; IX/X; X/XI; XI/XII. 



Testes. — The testes are slender and short, and connect 

 directly with the minute, sac-like sperm-sacs, which are 

 only slightly wider than the testes. Each testes has a cen- 

 tral core of connective tissue, or muscular strands project- 

 ing from the septum, which I once mistook for a duct. 



S -perm-ducts and Prostates. — The ducts join in the ante- 

 rior part of the clitellum, but their lumens do not fuse until 

 reaching the anterior third of XVII. After fusing, the 

 ducts are slightly widened and increase gradually but very 

 slightly in size until the body-wall is reached, where quite 

 a little swelling is seen at the point of junction with the 

 ducts. The sperm-duct joins the prostate before the two 

 have fully penetrated the wall of the papilla. The pros- 

 tates do not extend beyond the clitellum. The prostate 

 cells are of two kinds: those most numerous are composed 

 of glandular cells with very fine granulations taking the 

 eosin stain; the others, which are fewer in number, consist 

 of thin, rather irregular supporting cells, extending from 

 the peritoneum to the lumen. The latter are probably the 

 phylogenetic ancestors of the inner layer of cells which is char- 

 acteristic of the prostate of the higher Terricol^ (fig. 133). 



Ovisacs. — The oviducts are long and slender, opening in 

 front of set« ab. There are two small ovisacs in line 

 between the oviductal funnels projecting into somite XIV. 



Subgenus Enicmodrilus, subgen. nov. 



The various species of the subgenus Enicmodriltis may be arranged as 

 follows: — 



I. Sperm-ducts with a thick muscular investment near the pores. 



O. agricola Eisen. 

 O. Roses Eisen. 

 O. contractus Eisen. 

 I' Sperm-ducts without thick muscular investment near the pores. 

 II. Setae a<5 wanting in XVII. 



a. Sperm-sacs only in XII. O. mexicanus, sp. nov. 



(3) December 16, 1899. 



