94 
ZOOLOGY OF THE FAR EAST. 
having investigated the three species of Limnodrilus found in and near Tokyo, con- 
cluded that Hatai had confused more than one species under the name L. gotoi, since 
that author's description did not correspond in certain essential points with any form 
which was actually found, but appeared to represent a combination of features from 
two separate species. He retained the name L. gotoi for one of them, and called the 
other L. willeyi. A Limnodrilus from Ceylon, received through Dr. Willey, then 
resident in Colombo, is stated in the same paper to be identical with L. gotoi as newly 
defined by the author. In a postscript to his paper Nomura states that he is of 
opinion that L. socialis and his L. gotoi are identical. 
With regard to Nomura's criticism of Hatai's description, it appears to me to be 
rather daring to suppose a confusion on Hatai's part between two species which are 
really (if Nomura is right) so very distinct as his L. gotoi and L. willeyi. To mention 
only the most striking points of difference, the two species are at variance in the 
matter of the anterior sperm-sac (single in one, double in the other), in the presence 
or absence of spermatophores, and in the length of the chitinous penis-sheath (3 — 4 
times as long as wide in one, 10 — 11 times in the other); the last two characters at 
least are of extreme importance either in the differentiation of Tubificids in general 
or of the species of this particular genus. Hatai remarks that his worm "occurs 
abundantly in ditches and gutters of this city (Tokyo) throughout the year ' ' ; other- 
wise the fact that such a form was not found in Nomura's collections would be no 
proof that such a form does not exist ; since his collections were made many years 
subsequently to Hatai's, and Limicolae have a way of disappearing suddenly from a 
locality and leaving no trace. I found Branchiodrilus hortensis for a few weeks in 
Lahore some years ago, but have never met with it here since; and if I concur in 
Nomura's conclusion, it is partly because his knowledge of the localities and local 
conditions enables him to speak with some authority. Hatai's two figures of the 
chitinous penis-sheath however certainly do seem to belong to two different animals. 
The next point is Nomura's identification of his L. gotoi with my L. socialis. 
The only differences on which he comments are those relating to the "septal sacs"; 
which appear to have a slightly different distribution and relative size; and to the 
dorsal blood-sinus on the intestine in segment ix, absent in his specimens, present 
in mine. These are points of slight morphological importance, the septal sacs being, 
as I believe, only aggregates of modified peritoneal cells and the sinus (observed by 
me principally in the living condition, where the colour of the blood renders it more 
easily visible) contracting or perhaps disappearing as a definite space in the preserved 
specimens. There are a number of other unessential differences; but there also two 
of much greater importance, which Nomura likewise leaves out of the discussion 
altogether. 
Firstly, the figures of the chitinous penis-sheath do not suggest the same shape, 
Nomura's showing a flange-like expansion round the open end, mine (a section) a 
strongly upturned margin on one side only ; nor do the descriptions seem altogether 
to correspond. The difference is in some degree due to the mode of presentation ; I 
give herewith (fig. 7) a figure of the isolated penis-sheath of one of the present Kyoto 
