STUDIES ON EARTHWORMS. 291 
the fibrous portion of the cord (n.fi.), and clearly shows its 
separation into two halves. Amongst the nerve-fibres round, 
nearly homogeneous, nuclei are seen scattered about, which pro- 
bably belong to this connective tissue. 
As to the position of the cerebral ganglia, since the first 
sub-pharyngeal ganglion lies in the fourth annulus—i. e. somite 
11—then the cerebral lie in the second or third annulus—i. e. 
somite 1. Owing to the absence of septa in this region it is 
impossible to say, with certainty, exactly in which annulus they 
lie, but since they lie in front of the first suabpharyngeal, the posi- 
tion of which is easily determined, they are at any rate in somite 
1. Perrier considers it a rule that the cerebral ganglia of Earth- 
worms lie in the third somite, and never in the first; but here 
at any rate is anexception. Beddard mentions that the cerebral 
ganglia of Typhceus lie in somite 1, and probably other 
worms will show that his rule does not invariably hold good. 
The question, however, occurs, Do the annuli of Microcheta cor- 
respond to the somites of Lumbricus in this region of the body ? 
From the cerebral ganglion, there pass three or four nerves, 
forwards, on each side to the prostomium (figs. 34, 35, np.). 
From the commissure, close to the cerebral ganglia, there pass 
forward three or four nerves, for the number varies in the two 
specimens, to the wall of the buccal region (n. B.) ; from nearly 
thesame position, but passing backwards, are nerves to the 
pharynx; and similar pharyngeal nerves come off from the 
hinder part of the commissure, both dorsally and ventrally (n. ph); 
these probably enter a “‘ visceral system” in the alimentary canal, 
which I have not followed out. 
Summary.—The chief points which are new or noticeable 
about Microcheta are as follows: 
(1) The small prostomium. 
(2) The numerous annuli that make up a somite, more 
especially in the case of the anterior somites. 
(3) The small size of the sets, relative to the size of the 
worm. 
(4) The large size of the nephridiopores, and their arrange- 
ment in a line with the lateral sete. 
