THE NEPHRIDIUM OP LUMBRICUS. 311 



made auy observations as to the different characters presented 

 by diflFerent parts of the tube except Beddard. I have, therefore, 

 examined sections through a number of earthworms of different 

 genera, in order to ascertain how far there is any general agree- 

 ment between their nephridia ; and I find that such an agree- 

 ment is present, with the exception that the muscular region 

 exhibits a great variability, sometimes being entirely absent 

 (as in Criodrilus), sometimes being enormously developed (as 

 in Microchseta), and in other cases presenting intermediate 

 conditions. 



The nephridium of the undermentioned worms presents the 

 same three regions that I have described for Lumbricus, 

 viz. (1) a non-ciliated narrow tube; (2) a ciliated middle tube; 

 and (3) a non-ciliated wide tube, which has frequently a wall 

 of irregular thickness. In all cases the whole of these three 

 regions is intra-cellular, and this may dip into the body-wall 

 directly, or enter (4) an intercellular muscular duct as in 

 Lumbricus. The funnel, however, presents a good deal of 

 variety in structure, as I will describe below in section 4. 



The worms I have examined^ are Criodrilus (for a drawing 

 of funnel see Vejdovsky, 32). 



AUurus (see Beddard, 4, pi. xxv,fags. 11, 12, and Vejdovsky, 

 32). 



Microchseta (see Benham, 8, pi. xvi, figs. 21 to 26; pi. xvi 

 bis, figs. 31, 32, 33). 



Urobenus (see Benham, 9, pi. viii, figs. 18, 19). 



Brachydrilus. 



Rhinodrilus (see Beddard, 1«, pp. 160, 161; and Horst, 

 21, fig. 8). 



Urochseta (see Perrier, 26, pi. xvi, figs. 38, 39; Beddard, 

 3, pi. V, figs. 5 to 9; Beddard, 6, pi. xxiii). 



Diachseta (see Benham, 9, pi. ix, figs. 27, 28). 



Perionyx. 



1 It may be worthwhile to add references to the figures of complete nephri- 

 dia, but which give no histological detail of other genera : 

 Hormogaster, Rosa, 28, fig. 8. 

 Moniligaster, Horst, 21, fig. 2. 



VOL. XXXII, PART III. — NEV^ SEE. X 



