6 Proceedings of Royal Society of Edinburgh. [sess. 
walls and septa, particularly in the anterior region of the body, and 
in the corresponding vascularity of the integumental layers. 
It differs from all earthworms in the following points: — 
1. The vas deferens is single on each side; it only occupies a 
single segment, or at most two. 
2. There is only a single pair of testes, which may be in 
segment IX. 
3. The sperm-sacs are a single pair with a simple cavity, i.e., 
not divided up by trabeculae. 
4. The atrium opens on to X/XI; its structure is that of the 
atrium of Rhynchelmis. 
5. The oviduct opens into segment XI. 
6. The clitellum occupies segments X-XIII. 
7. The egg-sacs are very large, occupying about three segments. 
In these points it approaches various Limicoline genera. 
The following are the principal facts in the anatomy of my species 
of Moniligaster. Those statements marked with a dagger (f) are 
made for the first time in the present paper : — 
tl. The prostomium is very small, not extending on to the 
peristomial segment. 
2. The setae, are strictly paired, and entirely upon the ventral 
surface of the body. 
f 3. The setae are not peculiar in shape, but like those of earth- 
worms; only the anterior pairs are larger than the posterior. 
f 4. There are no penial or copulatory setae (?). 
f 5. Dorsal pores are present. 
f 6. The mesenteries separating segments V/YI, YI/YII, 
VII/VIII, VIII/IX are very much thickened. 
f 7. The hearts are in segments VI-XIV, and are of large size. 
|8. The alimentary tract begins with a buccal cavity leading 
into a pharynx; the pharynx is well developed; the oesophagus is 
lined with a cuticle, it is very wide; the gizzards are three* in 
number, and lie in segments XIV-XYI ; there are no (?) calciferous 
glands. 
f 9. The nephridia commence in segment Y; each has a saccular 
diverticulum. 
* In one specimen, not M. Barwelli, the gizzards are situated further back, 
but I am not sure how many there are, and where they begin. 
