ZOOLOaiCAL RESULTS OF A TOUR IN THE FAR EAST. 
HIRUDINEA. 
By Dr. Asajiro Oka, Tokyo. 
(With Plate VII.) 
The collection of leeches made by Dr. N. Annandale during his trip to Japan, 
China and Siam, in 1915 and 1916, was placed in my hands for determination. I 
heartily thank Dr. Annandale for allowing me the privilege of examining the speci- 
mens, some of which proved unusually interesting. 
The material contains fourteen species arranged in ten genera, representing all 
the four families into which the non-chaetiferous leeches are now divided. They are 
mostly known forms previously described from Japan or China, only three of the 
species being new to science. Two of the latter, however, are such peculiar forms 
that it was found necessary to establish a new genus for each. One of these, 
Ancyrohdella biwae, n. g., n.sp., is a curious little Glossiphonid, much resembling an 
Ichthyobdellid in external appearance. It was taken from the bottom of Lake Biwa 
at a depth of 260 Japanese feet (about 80 meters), and is characterised by the pre- 
sence of three comparatively large hooks near the tip of an extraordinarily long 
proboscis. The other one, Myxobdella annandalei, n. g., n.sp., is a strange-looking 
Hirudinid with exceptionally soft body, collected in a small streamlet on the Peak, 
Hong Kong, about 1000 feet high, and is readily distinguished by the unique character 
that the furrows separating the somites are decidedly deeper and much more con- 
spicuous than those separating the annuli. The third new species, a Hemiclepsis from 
Siam, is interesting in so far as it occupies a position intermediate between that 
genus and Placobdella. 
With regard to the generic names of leeches, it should be remarked that a large 
number of genera now recognized are based solely upon external characters without 
any regard to internal structure, so that they require a thorough revision when their 
anatomy has been sufficiently worked out. My own studies on Japanese leeches con- 
vince me that such a revision would necessarily result in the suppression of numer- 
ous old genera and the formation of no less new ones, with the corresponding re- 
arrangement of the species. In the present paper, however, I have intentionally 
abstained from making any such attempt and have employed the generic designa- 
tions simply as they are now used. It might perhaps be noticed here that the 
discrimination of such genera as Placobdella, Blanchard (1893), Mimobdella , Blanchard 
(1897), and Scaptobdella, Blanchard (1897), from their nearest allies is, in certain 
cases, a matter of great difficulty, if not of impossibility. 
