SOME LITTORAL OLIGOCHAITA OF THE CLYDE. 45 
ampulla without definite external demarcation between the two, and, as a rule, 
narrowing gradually towards the external aperture, so as to form an elongated and 
inverted cone. The lumen of the duct is narrow throughout; the cells of which the 
inner layer of its wall is composed are covered by a conspicuous layer of muscular fibres, 
arranged longitudinally ; a cord of some hyaline matter (? coagulum) almost fills the 
lumen of the duct, in which may also lie a few spermatozoa. The duct is slightly 
invaginated into the cavity of the ampulla, though this is not evidenced externally ; 
there is consequently a circular trough around the ampullary opening of the duct, and 
in this trough the spermatozoa frequently lie coiled (Pl. I. fig. 7). Surrounding the outer 
end of the duct is a fairly large lobulated gland, the cells of which are continuous with, 
and a modification of, the external epithelium round the aperture. Their inner ends 
are prolonged for a considerable distance within the muscular coat, as in other forms 
(Pl. I. fig. 8) (cf L. subterraneus, Enchytreus albidus, L. viridis), The whole 
of the gland-cells are behind the level of septum 4, and the aperture is thus not in 
the interseemental furrow, but posterior to this, on the anterior part of segment v. 
The characteristic trumpet or funnel-shape previously referred to is due to the 
gradual increase in the external diameter of the duct as it is followed inwards (the 
lumen is narrow and of the same diameter throughout); the margin of the funnel 
(fig. 5a) is the optical expression of the junction of the thick-walled duct with the thin- 
walled ampulla; a small inner circle is the opening of the duct into the cavity of the 
ampulla. 
The clitellum extends over segments xii. and xiii. 
The intestine, in its anterior part at least, may be full of sporozoan parasites. 
I was for some time undetermined as to whether I should unite this form with 
Lumbricillus (Pachydrilus) litoreuws, Hesse (9). Though the descriptions agree in a 
number of points, they vary slightly in certain others, and considerably in the 
following: (1.) The length of the present form may be nearly twice that given for 
L. litoreus ; (ii.) the number of sete in the ventral bundles is four to six or seven in 
the present form, six to ten in L. litoreus; (iii.) the ccelomic corpuscles are more 
various in form, and contain a nucleus which is obvious in the fresh condition in the 
present species ; (iv.) the copulatory glands occur in segments xiii.—xvi., 7.e. extend one 
segment farther back than in L. litoreus. 
The chief distinction, however, is in (v.) the spermathecze and their ducts; in L. 
litoreus the ampulla, according to the original description and its accompanying figure, 
is of comparatively large size, elongated in shape, with walls of the same thickness 
throughout, gradually merging into the duct, which latter is much shorter than the 
ampulla, and has two separate glandular masses at its aperture. In the present form 
the ampulla is small, subspherical, with extremely thin walls in its equatorial portion, 
thicker near its junction with the cesophagus ; there is, internally, a very sharp demar- 
cation between ampulla and duct, the latter being much longer than the ampulla, and 
being surrounded by a complete circle of large gland-cells at its aperture. The very 
