NEW ENCUJSH GENUS OP AQUATIC OLIGOCHJITA. 165 



At the pore the columnar epidermal cells dip iu slightly to 

 meet the already superficially situated duct. 



The structure of the sperm-sac is represented in fig. 23. The 

 cavity is very greatly subdivided by muscular (?) trabeculae 

 (trab.), which diverge from an axial bundle {ax.) continuous 

 with the septum. The spaces between the trabeculse are 

 occupied by developing spermatozoa ; the outermost lobules 

 contain usually the younger stages, whilst the more advanced 

 stages occupy the central lacunae. This arrangement, how- 

 ever, as a glance at the figure will show, is not absolute, 

 young spermatozoa frequently occurring in the outer lobules, 

 whilst sperm-morulse are found centrally. 



The Female Organs (fig. 11). 



The pair of ovaries lie in Somite xiii ; the oviducts have 

 the usual relations, and open on Somite xiv, just within the 

 line of the ventral chsetse ; a small ovisac occupies the usual 

 position. 



The ovary itself is large, and extends across its segment 

 almost to the hinder septum ; its narrow neck is relatively 

 long ; its tail, too, consists usually of eight ova in a single row. 

 These ova are not noticeably larger than those of Lumbricids, 

 measuring '3 mm. 



The relation of the ovisac to the 13th somite and to the funnel 

 of the oviduct deserves a description, as it is sometimes inferred 

 that the ovisac has no direct communication with the duct. 



I give four drawings from a series of transverse sections 

 through the funnel of the oviduct. 



In fig. 2Ji, the first section in the series which cuts the 

 funnel, we see the dorsal and ventral lip with a narrow aper- 

 ture (ov.f.) into Somite xiii. 



In fig. 25 (next section in the series) the folding of the 

 funnel is evidenced by the discontinuous edge, a portion of 

 which opens directly into Somite xiii (ov.f.); another portion 

 {ov.f.), itself folded, communicates solely with the ovisac. 



In fig. 26 (two sections further on) the septum separates the 



VOL. XXXIV, PART II. NEW SEE. M 



