DEVELOPMENT AND ANATOMY OF SOME EARTHWORMS. 25 
stages now described resemble very closely those described by 
that author in dealing with Megascolides australis 
(‘ Archiv fiir mikr. Anat.,’ Bd. xl). 
In an embryo such as that from which figs. 5—8 and 33 
are taken it is quite clear that the nephridia arise as paired 
structures, a pair in every segment except perhaps the first. 
Nephridia 7 and 16—19, from the right-hand side of this em- 
bryo, are shown enlarged in figs. 34, 35. 
Each consists of a preeseptal funnel, a neck connecting the 
funnel with the glandular loop, and an excretory duct. 
The funnel is at no stage well developed, and is probably 
never functional, and afterwards entirely degenerates. 
This neck becomes afterwards a very important structure, 
and is dealt with below. 
The glandular loop arises by budding from the neck region 
and rapidly enlarges, ductules develop within it, and it becomes 
a very complicated structure, as shown in fig. 35 and in outline 
in fig. 39. It certainly corresponds to a macronephridium of 
Megascolides, but its further development becomes arrested, 
and I have been unable to distinguish it in the adult from the 
loops of the micronephridia which subsequently appear. 
It is important to note that owing to the imperfect state of 
development of the septa these loops are by no means confined 
to their own segments. 
The excretory duct also arises from the neck region asa solid 
outgrowth (fig. 34, neph. 17; and fig. 37, ex. d.) ; it very soon 
acquires a lumen and opens to the exterior. It elongates 
rapidly, more than keeping pace with the body-wall] in its 
growth, and the aperture comes to lie very dorsally; the ex- 
cretory pores of all the nephridia in front of nephridium 17 lie 
outside the preparation in fig. 33. 
The series figs. 836—39, taken from an older embryo, traces 
the further development of the nephridia ; the figures represent 
the 7th, 55th, 75th, and 86th nephridia respectively. Fig. 39 
represents, therefore, a later stage in the development of the 
nephridium of fig. 35, but figs. 836—88 represent stages in the 
development of nephridia which did not exist in the embryo of 
