boa -FRANK E. BEDDARD. 
The connection thus formed between the first and second 
nephridia recalls the statements of Hatchek with regard to the 
development of the nephridia in Polygordius. I have lately 
pointed out that in a Eudrilid Libyodrilus (10) such a con- 
nection is soon established between successive nephridia; but 
in all these cases the paired nephridia are developed first, and 
the connection is brought about later. There are, however, 
plenty of analogies which might support the view that there 
has been an acceleration in the development of the nephridia, 
the connecting duct being developed later and later until it 
ceased to appear at all, 
However, it is in any case evident that the ‘‘ pepto-ne- 
phridia” of Acanthodrilus are compound structures repre- 
senting the two pairs of nephridia of the first three segments. 
It is quite possible that the corresponding organs in other 
earthworms have a similar history. It is very noticeable that 
in earthworms which have no pepto-nephridium the nephridia 
do not commence before the third segment ;! in Lumbricus 
this is the case, andin Urobenus, Acanthodrilus, and Rhi- 
nodrilus. Microcheta appears to be an exception; but 
the segmentation of this form is not yet definitely made out. 
In these worms, therefore, I should expect to find a “ head 
kidney ” lying in the first two segments of the larva, while in 
forms which havea pepto-nephridium I should expect that this 
organ will prove to be a permanent “head kidney” plus the 
following one or two nephridia. 
The next important fact of general interest to be noticed 
about the development of the nephridia in this Acantho- 
drilus is their paired condition in the embryo. 
The facts that I have been able to make out in the ontogeny 
segment. Dr. Rosa has suggested that I have accidentally referred to the 
mucous gland a funnel which should belong to the following nephridium. I 
would point out, in reply, that it is very possible that the development of the 
first pair of nephridia in Urocheta is like that of Acanthodrilus; in 
this case the existence of more than one funnel would be not surprising. 
1 Later, of course, in such forms as Pontodrilus, but never before that 
segment, 
