CONTRIBUTIONS TO THE ANATOMY OF EARTHWORMS. 473 
wall between the longitudinal and the circular muscular coat. 
Iam not certain whether the two nerves meet dorsally, but 
they certainly do ventrally (see fig. 2, 2. a). These nerves give off 
innumerable branches, for the most part from the upper surface 
of the nerve-trunk, i.e. towards the epidermis. These nerve- 
branches consist, like the nerve from which they arise, of 
numerous delicate fibres, which have usually a somewhat wavy 
aspect. Among them are many nuclei which may belong to 
the nerve-fibres or to their sheath. As these nuclei were found 
on the smallest branches close to their connection with the 
epidermis it seems to be more likely that they are the nuclei 
of the nerve-fibres. 
The bundles of nerve-fibrils pass in every direction, as is 
shown in fig. 1, and appear to anastomose with each other, 
though I could not detect any ganglion-cells connected with 
them. ‘These nerve-branches finally terminate in connection 
with (?) the cells of the epidermis ; bundles of fibrils could be 
observed passing up into the epidermis, which were quite as large 
as the branches immediately arising from the main nervous 
trunk. I only observed the presence of this intramuscular 
nervous plexus in the immediate neighbourhood of the sete. 
Subneural Blood-vessel. 
The subueural blood-vessel, which does not appear to be 
present in any genera of Oligocheta which have been referred 
to Claparéde’s division of the Limicole, is also wanting in some 
Earthworms. Perrier has denied its existence in Pontodrilus 
and Pericheta, and Benham states that it is also absent in 
Michrocheta. It is therefore of some little importance to 
note that this blood-vessel is not invariably absent in the genus 
Pericheta (see fig. 7). 
I have found it in the following species : 
Pericheta, sp. (from the Philippines), 
P. aspergillum, 
but it is absent in P. armata.} 
1 T may also mention that the two latter species have no typhlosole, but 
that there is a rudimentary typhlosole in Pericheta, sp. (? affinis). 
