SOME LITTORAL OLIGOCHATA OF THE CLYDE. 43 
The ventral sete are usually four to six (occasionally seven) in a bundle—commonly 
six in the anterior, five in the posterior part of the body; there are no ventral setze 
in segment xii. The lateral setee are three to five in a bundle, except that in segment 
xu. there are only two, or one, or none. 
In length the sets: are about ‘07-08 mm., the ventral being on the whole a little 
longer than the lateral. 
The alimentary canal has the usual relations. Septal glands are present in con- 
nection with septa +, 2, and £; they are enclosed within the septa, which split to contain 
them, and thus suspend them to the body-wall; they are less bulky than in some other 
species. Chloragogen cells begin in segment vi.; they are very finely granular. There 
are no peptonephridia. The wsophagus, narrow as far as segment vil., dilates in a 
fusiform manner from vii. to x., and in this region it may be intersegmentally constricted 
like the intestine ; it is narrow in the genital seoments, and widens to form the intestine 
in Xv. 
The dorsal vessel begins in the thirteenth, fourteenth, or fifteenth segment, and 
bifurcates at the junction of the prostomium and first segment. The ventral vessel is 
distinct throughout the body, and bifurcates in segment iv. There are four pairs of 
lateral commissures; the first originates from the dorsal vessel in segment ii. and 
passes forwards into segment ii. ; the last belongs to the fifth segment. The blood is a 
light yellowish red. 
There are numerous body-cavity corpuscles, nucleated and granular, mostly of the 
form of circular, bean-shaped, or elongated pear-shaped discs; some appear to have the 
form of elongated needles. 
The first nephridium appears to be situated usually in segment viii. ; it was seen 
in vu. once, and once seemed to be in ix. The ante-septal portion of each is small; the 
margin of the funnel projects on one side as a tag, from which long cilia wave down 
the lumen of the tube; there are no outward cilia on the margin of the funnel. The 
post-septal portion is elongated, and in its anterior part is of a brownish colour (cf. L. 
subterraneus) ; the duct is shorter than the post-septal portion, and is directed obliquely 
downwards and backwards to the aperture; just within the aperture the lumen is in 
sections seen to be dilated to form a small ampulla. 
The cerebral ganglion is indented posteriorly, while its anterior border is almost 
straight; its lateral margins diverge somewhat posteriorly. The ganglion is about 
‘one-and-a-half times as long as broad. The ventral nerve-cord has “ copulatory glands” 
associated with it in segments xiil., xlv., xv., and xvi.; these closely embrace the cord 
laterally, but do not cover it on its dorsal surface. 
The testes are pear-shaped masses, in two groups, one on each side; they are attached 
to septum +? near the body-wall, laterally in the segment; the lobes themselves may 
be either in segments x. or x1., according as the movements of the animal force them one 
way or the other; the septum must therefore have considerable deficiencies. Sperma- 
tozoa usually occupy segments x. and xi., and may get forward into ix. 
