230 Dr. F. E. Beddard on the Genus Tricliodiilus. 



The iiephridia of Trichodrilus allohrogum are described by 

 Clapar^de; but my own observations upon this British 

 species do not agree in many particulars with his. I rely 

 entirely, as to this part of tiie anatomy of the worm, upon 

 longitudinal sections ; I was unable to make any trustworthy 

 ob-;ervations upon the living worm by reason of its opacity. 



Clapar^de remarks — and I am in agreement with liim — 

 that the nephridia are absent in tlie first six segments of the 

 worm. He found these organs in the Vllth and VTllth seg- 

 ments, but asserted their absence thereafter until the Xlllth, 

 where they again begin, and continue in following segments. 

 There is, I think, no doubt about the fact that, as in Phreato- 

 f^n'.v, according to botli Vejdov.sky * and myself f, the pairs 

 of nophridia are not necessarily limited to one segment. In 

 the present species the first pair lie in Vll., but extend also 

 through Ylli., IX., and a part of segment x. This was very 

 plain in my sections, and the continuance of the tube through 

 the septa quite clearly to be made out. I did not see the 

 funnel, which no doubt lies in segment VI., but I found the 

 duct leading to the external pore upon segment vil. In 

 segment xi. I could find no nephridia at all ; but in segment 

 XII. and the following these organs were again present. I 

 am not certain whether the difference between the species 

 described by mj'self here and that of Clapar^de, as is to be 

 inferred from his descrip'ion, is a real one; for recently 

 Bretcher, in an account of Bichceta sanguinea%, vviiich species 

 Piguet considers to be referable to the genus Trichodrilus §, 

 has mentioned that the nephridium of segment VII. traverses 

 also segment VIII. Nor can it be considered that the exten- 

 sion of this nephridium settles tiie identity of the genera 

 Trichodrilus and Phreatothr-ix (whirh Michaelsen would join) 

 on account of the conditions observable in other genera of 

 the family. 



In Stylodrilus vejdovshyi Benham |1 describes the first pair 

 of nephridia as extending through segments VII.— X. in pre- 

 cisely the same way as has been referred to above. 



In Lumhricnhis varlegaius Mrazek ^ found that a single 



* System, u. Morph. d. Oligoch. Taf. xi, fig. 18. 



t Proc. Zool. Soc. toin. cit. 



X " Siid-schweitzerische Oligochaeteu," Rev. Suisse Zool. viii. 1900, 

 p. 444. 



§ " Notes sur les Oligocbetos," Kev. Suisse Zool. xxi. 1913, p. 141. 



(I " Notes on some Aquatic Oligoclipeta," Quart. J. Micr. Sci. (n. s.) 

 xxxiii. p. 211. 



^ " lieitrage zur Naturgescbiclite von Lumhriculns" SB. k, Bolira. 

 Oes. 1913. 



