216 MR. F. E. BEDDARD ON A [Mar. 20, 



is colourless as in all the other species except ^. ehrenbergii, where, 

 according to Lankester \ it is of a pinkish colour. 



There are a large iiumher of pairs of nephridia present, while in 

 ^. variegatum there are only three pairs, occupying segments 4-6. 

 They are very readily visible, and the terminal" aperture into the 

 coelom is extremely obvious, lying midway between two successive 

 seta-bundles. The coelomic aperture can hardly be termed a 

 " funnel," as it is only just perceptibly wider than the' rest of the tube. 

 The external orifice of the nephridium is placed close to the median 

 ventral line. Although the segmentation of jEolosoma does not 

 affect the cceloni, there being no mesenteries present, it is clear that 

 the position of the nephridia is such that, were mesenteries to make 

 their appearance, each nephridium would be entirely contained in a 

 single segment ; the external orifice is in fact in advance of the cceIo- 

 mic aperture (fig. I). This is of some little importance, inasmuch 

 as in Ctenodrilus ", undoubtedly a near ally of ^Slolosoma, the single 

 pair of nephridia are entirely contained within the first segment of 

 the body. Again, in Polygordius^ the funnels of the nephridia, 

 although they come into close contact with the septum which 

 divides the segment containing the nephridium from the one in 

 front, do not actually perforate it. Polygordius is certainly a very 

 primitiAC Annehd ; and since the same conditions obtain in the 

 Capitellidse and other Chfetopods, there are some reasons for 

 believing that the restriction of a nephridium to a single segment is 

 primitive. On the other hand, it is almost universally the case 

 among the Oligochseta that the funnel lies in trie segment in front 

 of that which bears the external aperture of the nephridium. Again, 

 the nephridia of j^olosoma are, as has been pointed out by Vejdov- 

 sky, attached to the parietes by simple unicellular muscle-fibres. 

 This is perhaps to be looked upon as a primitive arrangement, since 

 the embryonic nephridium of AUololophora is, according to 

 Lehmann, attached in a similar fashion^. The characters of the 

 funnel are important ; so far as I can ascertain from a single fortu- 

 nate section (fig. 4) it is composed of only two cells ; there are at 

 any rate only two nuclei present, and one of these is rather in 

 advance of the other. It is a fact which favours some views which 

 I have put forward elsewhere ^ as to the origin of the Annelid from 

 the Platyhelminth excretory system, that in this primitive segmented 

 worm the nephridial funnel should be, at most, two-celled. As to 

 the structure of the nephridia, they consist, as in all Oligochseta, of 

 " drain-pipe cells." 



The difference in the number of the nephridia between the indi- 

 viduals which I have examined and those which Vejdovsky has 



1 Linn. Trans, vol. xsvi. 1869. 



^ The most recent paper known to me on this worm is by Dr. Scharff. 

 Q. J. M. S. vol. xxvii. n. s. 



3 Fauna und Flora des Golfes von Neapel, xiv. Monograph of Polygordius, 

 by L. J. Fraipont. 



■* Jeu. Zeitschr. 1888, pi. xx. flg. 7. 



' Q. J. Micr. Sci. 1888, pt. i. 



