680 



one end of which the vas deferens opens ; this hody is lined through- 

 out with a single layer of glandular looking cells, outside which are 

 several layers of muscular fibres and outside these again peculiarly 

 modified peritoneal cells. The structure of this body is in fact 

 identical with that of the atrium in Stylaria lacustris^. 

 There is thus an additional ressemblance to the vasa deferentia of the 

 lower Oligochaeta. 



The receptacula semi n is (seminal vesicles) appear on dis- 

 section to lie partly in segment 8 and partly in segment 9. Longitu- 

 dinal sections appeared to show that this was produced by the bulging 

 of the thin septum lying between segments 8 and 9 ; the funnel of the 

 vas deferens which I have not hitherto been able to describe'-^ is 

 situated in the interior of the receptaculum semi n is 'o as in many 

 other Lumbricidae ; it is a simple disc-shaped expansion as in 

 many of the lower Oligochaeta; among earthworms the vas 

 deferens funnel is usually much plicated. 



I have already called attention to the fact that the vasa defe- 

 rentia of Moniligaster ressemble those of the Naidomorpha 

 in being single and in being contained in two segments, the exter- 

 nal aperture in one and the internal funnel in the other. I am not 

 however quite certain that this is really the case ; the appearances pre- 

 sented by longitudinal sections would seem to indicate that the vas 

 deferens as well as the receptaculum seminis are con- 

 tained in a single segment. If this is really the case the con- 

 dition is paralleled in Stylaria where the funnels open into the 

 same segment as that which bears the external aperture, close to its an- 

 terior mesentery. Finally the position of the male pores on 

 the boundary line between two segments though not 

 found in any other earthworm is common among the 

 Limicolae. 



Ur. Horst describes a receptaculum ovorum attached to the pos- 

 terior side of segment 1 3 which evidently corresponds to the ovary of 

 Wl. Deshaycsi^^ I would point out that the justice of Horst's surmise 

 that this structure is really a receptaculum ovorum is borne out by 

 Perrier's figure of the minute structure of the corresponding organ 

 in M. Deshayesi^'^\ in this figure the organ is seen to be divided up into 



8 Vejdovsky, System u. Morphol. d. Oligochaeten. Vol. IV. fig. 10. 



9 Ann. and Mag. Nat. Hist. 1. c. 



10 This term is used to correspond with receptaculum ovorum. The term 

 vesicula seminalis, which has been used in the same sense, is better restricted to the 

 glandular portion of the atrium. 



'1 1. c. Vol. IV. figs. 77, 81 o. 

 12 1. c. Vol. IV. fig. 82. 



