THE LEECHES OF JAPAN. 349 
can live on land only where the air is loaded with water. They 
are not, therefore, to be regarded as the scattered and isolated 
survivors of a race that has passed the meridian of its career, 
aed are now verging to extinction, but as animals still on the 
road to terrestrial life. 
Although the distribution of these Leeches is now prepon- 
derantly insular, there are unmistakeable indications—at least 
in the case of the Japanese and Singhalese species—that they 
have sprung from a continental, stock. The close affinities 
between two species so widely separated as those of Japan and 
Ceylon are easily accounted for, when we remember the 
proximity of these islands to the same great continent. There 
can be but little doubt that they are to be explained on the same 
general principles that serve to account for numerous other re- 
semblances between the faune and flore of these distant islands. 
I believe that the progenitors of these two species, and probably 
all the remaining species, had their headquarters somewhere 
on the continent of “Asia, most likely on the slopes of the 
Himalayas. 
Hirvupo nipponia,' nov. sp. Pl. XVIII, figs. 10—20. 
Diagnostic Characters. 
Body has the shape and proportions of the European Medi- 
cinal Leech, but is much smaller. Figs. 18 and 20 represent 
two of the larger individuals, and figs. 12, 14, and 17, three 
of the smaller ones. The following measurements were taken 
from one of the larger specimens :— 
Length, swimming, 8°5 cm.; creeping, 10 cm. ; at rest, 3°4 cm. 
Width re 10 mnm.; 3 7 mm. 
Height _ 3-4 mm.; 3 4 mm. 
Greatest width a little behind the middle; tapering from 
this point towards the extremities, but more anteriorly than 
posteriorly. 
Cephalic lobe rather broad, and well rounded in front, 
composed of four annuli. 
1 Nippon, the native name for Japan. 
VOL, XXVI, PART 3.—NEW SER, AA 
