1908.] OLIGOCH.ETE WORM IJT ENGLAXD, 369 



apparently these nepliridia are confined to that segment, with 

 the exception, of course, of the funnels. In the following segment, 

 viz., viii., there was another pair of rather smaller excretory 

 glands. A third pair of the same size, or nearly so, w^ere to be 

 found in segment ix. Then followed a gap and the next pair 

 were in segment xv., extending, however, through the two 

 following segments as well — that is to say, three in all, exclusive 

 of the segment w^hich contains the funnel. Further back still 

 a j)air of nej)hridia extended through foui- segments which 1 

 have not mapped accurately. It is clear that in any case this 

 species shows some differences from both accounts given by 

 Yejdovsky. But the facts are not irreconcilable with his earlier 

 account, which, as I have suggested, may refer to the same species 

 which I consider here, or may merely lend evidence to the view 

 that the species varies in the number and position of its 

 nephridia. 



The generative organs appear to be like those of Phreatothrix 

 j}i'agensis, save in one respect. I have, how^ever, examined only a 

 single sexually mature individual. In Phreatothrix pragensis 

 there is a second pair of spermathecse in segment xii. rather 

 smaller than those of segment xi. I looked carefully for, but was 

 unable in my species to find, the second pair. I noted the 

 sperm-sacs to lie in segments xi., xii., and xiii. The sperma- 

 thecfe and atria open behind the ventral pair of sette, which are 

 present and have not disappeared. This is quite in accord with 

 Yejdovsky 's statements concerning Phreatothrix j^ragensis. 



To resume : this species from Cambridge appears to dififer from 

 that described by Yejdovsky from Prague in the following 

 points, viz. :— (1) The chloragogen investment of the gut begins 

 in segment vii. ; (2) the dorsal and ventral vessels divide to 

 reunite much further forward in the body ; (3) there are no con- 

 tractile appendages of the dorsal vessel ; (4) the number and 

 arrangement of the nephridia is somewhat difierent ; (5) the 

 spermathecae of segment xii. have totally disappeared. 



It seems to me that we have here a considerable number of 

 <lifierences which warrant the erection of a new species for the 

 worms from Cambridge, which I propose to term Phreatothrix 

 cantahrigiensis, or, in accordance ^s^itli Michaelsen's views *, 

 Trichodrilus cantahrigiensis. Possibly this second species with 

 nephridia extending through a considerable number of segments 

 may be regarded as furnishing an argument for reinstating the 

 genus Phreatothrix. On the other "hand, inasmuch as this 

 character is to be found in Stylodrilus-t vejdovshyi — a species 

 belonging to a genus where there are no contractile appendages 

 to the dorsal vessel, — the question of the generic distinctness of 

 other Lumbriculids is perhaps raised by the facts which I am 

 here able, to bring to the notice of the Society. 



* OHgocliseta in ' Das Tierreicli,' Berlin, Oct. 1900, p. 58. 

 t Benliam, Quart. Joiiru. Micr. Sci. vol. xxxiii. 1891, p. 42. 



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