■C92 



THE REPRODUCTIVE SYSTEM OF DIGASTEU, 



(b) Oviducts. — The oviducts are a pair of short ciliated tubes 

 with muscular walls, whose swollen ciliated funnels (fig. 1, f.o.) 

 open in the hinder part of segment xiii. After perforating the 

 mesentery between segments xiii -xiv., the tubes pass obliquely 

 downwards and backwards through the body wall to open by the 

 small oviducal pores (fig. 2 op. o.) situated, one on either side of 

 the mid line, in segment xiv. 



In one specimen examined, in addition to normal ovaries and 

 oviducts in the usual position, there is present an extra complete 

 oviduct (fig. 3, o.) on the left side in segment xii. This perforates 

 the mesentery between segments xii., and xiii., and opens to the 

 •exterior in the latter segment. An extra ovary was not observed. 

 >So far as I can learn from recorded cases of variation* in the 

 reproductive system of Oligochtetes, the present appears to be the 

 only case on record in which an extra oviduct has been found 

 iinassociated with a cori'esponding ovary. 



• (c) Spermathecce. — There are, as Fletcherf describes, " three 

 pairs of somewhat rounded or pyriform spermathecfe, a pair in 

 each of segments Aii.-ix., and of which the posterior pair are 

 sometimes the larger" (fig. 1, sj}.' sp." sp.'"). Each spermatheca 

 is furnished antero-ventrally with a small pear-shaped diverti- 

 culum, the stalk of which is connected with the duct of the 

 spermatheca. Their ducts, which are comparatively laro-e and 

 muscular, run backwards in the body wall to open " to the 

 •exterior two segments behind those which contain the sperma- 

 thecae to which they belong," viz., on segments ix., x., and xi. The 

 i^permathecal pouches are lined by a single layer of tall colunmar 

 non-ciliated cells and do not contain spermatozoa. Their ducts 

 are lined by an epithelium, which is not the same throughout its 

 extent. For about one-third of the thickness of the body wall 

 the lining consists merely of invaginated epidermis differing in 

 no way from that of the outer surface of the body. Over the 



* W. Bateson. Materials for the Study of Variation, pp. 160-165. 

 t I.OC. (it., p. 5-58. 



