229 



A comparison with fig. 1, where the clorsally situated nephri- 

 diopores are indicated ia the praeclitellean region , will show 

 that here the positiou of the dorsal uepüridiopores is comparatively 

 somewhat lower down. 



For this praeclitellean region I will here give the result of 

 careful »external" examination with an ordiuary magnifying lens 

 of two specimens, tabulated so as to show in the two middle 

 columns the segments in which the nephridiopores lie above the 

 4th seta , in the two outer columns those in which they lie just 

 above the second seta , right and left (see p. 330). 



The point of exclamation signifies that the nephrodiopore in 

 question is exceedingly distinct, the point of interrogation that 

 T remain in doubt whether there really was a nephridiopore in 

 the spot indicated. 



This explains how in a few cases three nephridiopores appear 

 to be indicated for one segment. One of these , most probably 

 that niarked »?", is in that case certainly not a nephridiopore: 

 sections never reveal any triplicity of the sort. 



We have above noticed that in the praeclitellean region the 

 dorso-lateral nephridiopores are generally in somewhat closer vici- 

 nity to the fourth setae, than iu the posterior region of the body: 

 we may now conclude from this list that their nuraber , in com- 

 parison to the ventro-lateral nephridiopores in this anterior body- 

 region , is also more considerable. Although only two specimens 

 have been (partially !) tabulated , I have verified this in a general 

 way for a much larger number. 



Both Lumbricus and Allolobophora were examined and as both 

 the external investigation and the microscopic sections yielded 

 similar results 1 have no scruple in figuring the sections that 

 were taken from a specimen of the common earthworm of which 

 an exact specific identification has not been made. 



These sections (PL XII, fig. 3 — 7) teach us that at the nephri- 

 diopore Np the cellular layer lining the nephridial tube passes 

 gradually into the cellular epidermis. This cellular coating is 

 very distinct iu the viciuity of the nephridiopore (fig. 3 and 5): 



