Aquatic Oligochaeta from Japan and China. 
97 
ated by a rather shallow but quite visible groove, and both of fair extent, as shown 
in fig 8. It is not very uncommon in earthworms to have one or a few segments at 
the anterior end without setae (in addition to the first, which of course is normally 
achaetous); but unless we are to suppose that the internal genital organs have an 
altogether anomalous position, that cannot be the case here; and we must, I think, 
suppose that the setae begin normally, i.e. on segment ii, the first segment being 
unusually long and biannulate, — even though this brings the male aperture into an 
anomalous po.sition on segment xiii. This seems to me much easier than to suppose 
that the ovaries are in xv, and the male apparatus correspondingly displaced. 
Internal Anatomy. 
Septa 5/6 to 12/13 are somewhat thickened, decreasingly so towards the hinder 
end of the series; 6/7 is perhaps the stoutest. 
I could discover no trace of a gizzard ; the intestine begins in xii or xiii, but the 
beginning is indefinite, and there is nothing except the increasing investment of 
chloragogen to mark it off from the oesophagus. There are no calcareous glands. 
The dorsal vessel is single, in the anterior part of the body at least. The lateral 
vessel, running longitudinally forwards on the body-wall from segment xiv, is con- 
spicuous. The most peculiar feature of the vascular apparatus is the disposition of 
the hearts; whereas in most earthworms these closely embrace the alimentary tube, 
here they appear in the dissection as long loops which extend outwards onto the 
body-wall, reaching when the animal is pinned out to a position well beyond that of 
the dorsal setae and not very far from the middle Hne along which the animal was 
opened. Even when thus stretched out they are still much curled and twisted; so 
that in their natural position in the living worm they must form extremely con- 
voluted loops. Being in the specimens almost empty of blood, they resembled neph- 
ridia at first sight; a closer inspection, and microscopic examination, revealed their 
true character. They occur in segments vii — xi, and decrease in size from behind 
forwards. 
The nephridia are absent from the anterior part of the body, the most anterior 
being in segment xv; on one side of one of the dissected specimens there was a 
minute one in xiv. In each nephridium two parts can be seen; one a somewhat 
flattened, lobed, opaque white mass near the external end of the organ, the other a 
twisted tube extending inwards towards the middle line. The white masses are con- 
spicuous structures in the dissection, and can be seen through the body-wall in the 
unopened worm. The ducts open to the exterior in the line of the ventral setae, 
just in front of the setae thernselves. 
The testes are in segments x and xi ; they were relatively large in these speci- 
mens, and free in the body-cavity. Funnels were identified in both segments. The 
vesiculae seminales, represented in both specimens by a pair of transparent empty 
sacs, are situated in segment xii; in both specimens also the one on the left side is 
the larger. . 
What is perhaps a pair of ''prostate" glands is present in segment xiii; each is 
