170 
ZOOLOGY OF THE FAR EAST. 
the only representative of the Hirudinea hitherto recorded from the bottom of a deep 
fresh- water lake of Japan. 
Shape and Dimensions. In external appearance this leech looks much more like 
an Ichthyobdellid than a Glossiphonid (pi. vii, fig. 11). The body is very slender, only 
slightly depressed, and almost cylindrical in the anterior region. It shows a faint 
constriction about the height of the genital orifices, so that we can distinguish, though 
not sharply, a neck and a trunk, as in the case of most Ichthyobdellids. The head 
is wider than the neck and forms a distinct anterior sucker. The skin is irregularly 
wrinkled all over, and the posterior sucker is very small. These characters led me at 
first to believe that this was possibly a fresh-water representative of the genus 
Pontohdella. A careful study of the internal anatomy, however, showed that it be- 
longed to the family Glossiphonidae. 
All four of the specimens are more or less curved, but not at all contracted, as 
is inevitably the case with other Glossiphonids placed in alcohol without narcotizing. 
The measurements are as follows: — 
The greatest thickness of specimen No. i is about 12 mm., the width of the head re- 
gion 07 mm., the diameter of the posterior sucker 0 5 mm. The worm is, thus, more 
than ten times as long as it is wide, a shape never met with elsewhere in the Glossi- 
phonidae. In this respect it comes nearer to the genus Piscicola among the Ichthyob- 
dellidae, which may become twenty times as long as wide when fully extended. In 
the neck region, which occupies about one-fourth of the whole length, the body is 
nearly circular in cross section. The trunk, on the other hand, is a little flattened, 
but still very thick, as the ratio of the breadth to thickness is nowhere greater than 
4:3. In contrast to Pontohdella and Piscicola the lateral margins are not wholly 
obliterated, but are distinctly visible as an obtuse longitudinal ridge along the greater 
part of the body. 
External Characters. The skin is on the whole smooth; neither large tubercles 
nor small papillae are to be found anywhere. But there are irregular transverse 
wrinklings all over the surface, which disturb the counting of annuli in some places. 
Generally there are three to five of rather distinct wrinklings on an annulus besides a 
number of much fainter ones. This, together with the slender shape of the body, gives 
the worm an appearance altogether different from an ordinary Glossiphonid. 
The colour in alcohol is a uniform ash-grey; Dr. Annandale told me that they 
were of a pale reddish tint when alive. There is no trace of pattern or stripes of 
other colour. 
So far as I could count with certainty, there are 68 annuli in front of the hinder 
sucker. As there are no external characters to depend upon, it was found necessary 
Specimen. 
Length. 
17 mm. 
15 5 mm. 
14 mm. 
13-5 ram. 
Wide. 
16 mm. 
i'5 mm. 
15 mm. 
No. I 
No. 2 
No. 3 
No. 4 
i'2 mm. 
