new Genus of Olujocluvta. 79 



examined. The cocloni was crowded with corpuscles, which 

 appeared, however, to be chiefly compacted together to form 

 an investment for the nephridia. 



The presence or the absence of an abundant coating of glan- 

 dular peritoneal cells upon the nephridia no longer distin- 

 guishes " earthworms " from " waterworms." Although tlie 

 majority of the latter have the nephridia covered with large 

 clear vesicular cells (" globules incolores " Claparbde calls 

 them), they are occasionally replaced by a thin layer ot 

 flattened peritoneal cells. On the other hand, in Phreoryctes 

 the " glandular " investment of the nephridia attains very 

 great dimensions. In earthworms the rule is perhaps for 

 the nephridia to be coated with only a thin layer of peri- 

 toneum. Perrier was the iirst* to draw attention to the fact 

 that in this group also there i?, no uniformity; for in PontO' 

 driliis an investment of the nephridia occurs which is fully 

 as thick as that which covers the nephridia of Phreorjjctes. 

 The Eudrilidffi nearly all show this structural peculiarity; 

 for example, Libyodrihis f and Megacheeta \. In Ocnero- 

 drilus, Avhicli I regard as the nearest ally of Gordiodrilus, 

 the nephridia have been described by me § as partly imbedded 

 in a huge mass of clear cells. These cells are often (e. g. in 

 Heliodrilus^ Hyyeriodrilus^ and Lihyodrilus) loaded with 

 spherical bodies, which are probably to be regarded as excre- 

 tory products. But in that case the accumulation of such 

 cells round the nephridia — themselves excretory organs, seems 

 to be superfluous. Kiikenthal 1|, however, is of opinion that 

 these " lymphoid cells " are related rather to the blood-vessels 

 than to the organs (e. g. the nephridia) which they and the 

 blood-vessels cover. 60 far as concerns the nephridia in the 

 Eudrilid^e, there is no objection to this view. But in 

 Ocnerodrilus the nephridia have no blood-vessels, and yet an 

 abundant covering of the cells in question occurs. Kiiken- 

 thal believes that these cells extract waste products from the 

 blood, and finally breaking down in the coelom set free their 

 accumulated stores of excreted matter which reach the ex- 

 terior via the nephridia ; this, of course, only applies to the 

 lymph-cells with brown granular contents whicli clothe the 



* " Etudes sur I'orgariisation des Lvinhricicns terrestres : IV. Orgaui- 

 satiou dt's I'ontodn'hcs (E. P.),' Arch. d. Zool. Exp. t. ix. p. 205. 



t Beddard, "On the Structure of au Earthworm allied to Nemertu- 

 driltis," &.C., Quart. Jouru. Micr. Sci. vol. xxxii. p. 5554. 



X ^lichael^eii, /oc. cit. 



§ " On the Anatomy of Ocnerodrilus (Eisen)," Traus. ftoy. See. 

 Edinb. vol. xxxvi. pt. ii. p. 56.3. 



II " Ueber die Ivmphoiden Zelleu der Anneliden," Jen. Zeitschr. 

 Ed. xviii. p. 319. 



