new Species of Harthworms. 61 
oval one. It is while fixing the animals that the body 
becomes four-cornered, and in the struggles snaps occur at 
different parts, leading to complete separation. The quadri- 
lateral nature of the body is produced by the sudden con- 
tractions of the transverse bands of coelomic muscles, which 
extend from seta-space le to below the intestine. These 
muscles (fig. 3, A & B), which start from the body-wall in 
the median line, spread outwards in the form of a cone on 
either side, anda pull on the body-wall on the sides accounts 
for the lateral canals and dorsal and ventral corners. The 
contraction of the vertical muscles of the septa, which 
extend beyoud the grooves on either side of the body-wall, 
would produce the dorsal and ventral canals. The secondary 
sets of cwlomic muscle-bundles do not occur in front of the 
segment 14, and hence this region remains round. 
But the most interesting fact connected with these 
muscles is that they almost form, being connected here and 
there in their course by patches of peritoneal membrane, 
secondary ventral chambers, in which the nephridia are 
lodged. They have to be disengaged from these chambers 
for a more detailed examination. Numerous bubbles of air 
escape from these secondary chambers, as in other freshwater 
species, while the worms are opened and spread out, and, 
where the pressure has not ruptured the investing membrane 
of the ventral ccelomic chamber, very large air-bubbles are 
noticed, being entangled within the muscular mesh. Such 
air-bubbles are found throughout the worm. The chamber 
on ove side communicates with its fellow on the opposite 
side below the intestine and the nerve-cord, the associated 
vessels and the nephridia lie within the secondary cavity. 
In cross-section the chambers lock like two cones, their 
apices meeting in the middle. The upper wall is composed 
of several bands of muscles, held together imperfectly in 
most places by the reflected portion of the peritoneum from 
the intestine. On the body-wall (bc) the bundles of muscles 
at their point of insertion spread out in the form of a 
fan. Occurring in the narrower middle portion of the 
chamber, and also in the outward part, are clumps of large 
polygonal cells with one or more deeply staining nuclei 
associated with the muscle-bundles. Mixed up with these 
clumps are ccelomocytes and a fine plexus of blood-capil- 
laries. In any teased and stained preparation of the muscle- 
fibres, the cell-clumps are a striking feature, and occur 
uniformly. I am unable to trace the source or determine at 
present the nature of the origin of these cells, which may be 
due perhaps to the proliferation of peritoneal cells, which 
