STUDIES ON EARTHWORMS, 287 
trunk, and on arriving there it is sent forwards (Pl. XVI, 
fig. 20). 
The blood thus poured into the dorsal trunk has been aerated 
on the body wall and purified in the network on the nephridia, 
and is then sent forwards, some of it passing to the intestine, 
where it gathers nutritive material, which it pours into the typh- 
losolar trunk, and thence back into the dorsal trunk. 
With regard to the course of the blood in the lateral trunks, 
it is difficult to be certain whether it is backwards or forwards ; 
whether they collect blood from the network on the pharynx, 
from the cesophagus and septa of this region, and pour it into 
the network on the wall of the intestinal gland in somite 1x; 
or, on the other hand, whether they collect the blood from 
this gland, and pass it forwards to the pharynx, receiving fresh 
supplies from the alimentary tract on its way, as well as aerated 
blood from the body wall, &c. 
It is this latter alternative that Perrier adopts in the case of 
Urocheta, where the lateral (or “‘intestino-tegumentary’’) 
trunks have a similar disposition ; soit is probably here. Thus 
these lateral trunks will resemble the dorsal trunk, and the 
typhlosolar trunk, in the direction in which the blood is going. 
Microcheta agrees with Pontodrilus and differs from most 
other Earthworms in the absence of a subneural trunk. - 
The Nephridia.—One of the most noticeable features in 
Microcheeta is the size and shape of the nephridia (Pl. XV, fig. 
2). The apertures have already been mentioned as being in a 
line with the lateral setze, in the usual position, in the anterior 
region of the somites. The nephridia themselves lie close to 
the anterior septa of the somites, and each is very like Perrier’s 
figure of the first nephridium of Urocheta—his “glande a 
mucosité.”” 
Each nephridium consists of three parts (Pl. XVI, fig. 21) : 
(1) A large vesicular portion, communicating with the 
exterior on the one hand, and on the other with (2) a rosette 
of tubules, from which a branch passes through the septum 
to (3) the internal funnel. 
(1) The vesicle (ne. v.) (fig. 21, Pl. XVI) is a very large, 
