1887. J ANATOMY OF EARTHWORMS. 'Ml 



greater portion tbrms a tut't situated in the neighbourhood ot the 

 ventral pair of sette (c), between these and the nerve-coid; the distal 

 extremity of the tubuh^ ojiens by the ordinary funiiel-sliaped aper- 

 ture {a) into the next segment in front. 



Tlie excretory tubule then widens out, and forms a section (6) 

 which pre-ents a close structural agreement with tbat lettered (</) in 

 my figures of the nephiidia of Thamnodriius^; this opens into the distal 

 section of the organ (a) wliich runs paiallel witli the last ; its walls 

 appear to contain a few muscular fibres. A histological account of 

 the several legions of the iiephridium is deferred for the present. 



§ Generative Organs. 



Female Generative Apparatus. — I have investigated the structure 

 of the female geneiative organs by dissection as well as by means of 

 transverse and longitudinal sections through the region of tbe body 

 which they occupy. The excellent state of preseivation of the spe- 

 cimens enahles me to add some few facts to those which I have 

 already publislied ^ concerning tbe anatomy of the female reproductive 

 organs. I have also been able to obseive some facts btaiing upon 

 the development of the ovarian ovum, but these 1 propose to mal<e 

 the subject of a separate paper. 



The main facts with respect to the anatomy of tbe female lepro- 

 ductive organs !^tated in my former papers, 1 am able to confirm 

 from tlie study of the present species. In E. sylvicola as in E. boyeri 

 (and probably in all other species) the ovary is continuous with a 

 much-coiled duct with ciliated lining epitbelium and muscular v^alls 

 (Plate XXXlll. fig. 12) ; this opens on to the exterior in common 

 with a large speimatheca, upon tiie duct of which a ^mall gland is 

 sessile. 



A dissection of the present species shows that the female repro- 

 ductive organs, although opening on to the exterior in the 1-lth 

 segment, occupy both this and the 13th segment ; the mesentery 

 between tlie two segments is apparently absent. An examination of 

 a seiies of longitudinal sections sho«s tbat the mesentery is not 

 entirely aborted ; the large spermatleca lies in both segments, and 

 the mesentery dividing tliem is attached to the sides of the tperma- 

 theca; lower down (see woodcut, tig. 1, p. 381) the mesentery, when 

 present, divides off the ovarj', which lies in the 14th segment, from the 

 oviduct, the greater part ot which lies in tbe l,'3th segment, and fiom 

 the glandular diveiticulum of the i-peimatheca which lies in the same 

 segment {sp, fig. 1). Since the female generative aperture lies in tbe 

 14th segment as well as the ovary, it is clear that the oviduct, the 

 greater part of which lies in the 13th segment, must perforate the 

 intersegmental mesentery twice. 



It is clear fiom my sections that the relative positions of the ovaiy 

 and its duct are precisely the reverse of that which is indicated in 



1 Woodcuts, figs. 5, 6, P. Z. S. 1887 (pp. 160, 161). 



= Zool. Anzeiger, Bd. ix. p. 342 ; P. Z. 8. 1886, p. 1'02 ; Proc. Roy. See. Edinb. 

 no. Vl'l, p. 6. 



