JAPANESE LAND LEECHES. 285 



Acetahiduiii, small, ovate, the diameter measuring ab(3ut one-half 

 the width of the animal. 



Anas, on the dorsal surf ice of the acetabulum, al^out one ring's 

 breadth behind the posterior margin of the last ring. 



Of this leech there are 10 specimens in my collection. Only 4 of 

 them are mature. The dimensions are as follows : 



Lenofth, 7(S mm. 77 mm. 72 mm. 6(S mm. 



Width, 6 mm. 5.5 mm. 5 mm. G mm. 



■ Depth, 4.5 mm. 4.5 mm. 4.5 mm. 4 inm. 



By com|)aring the rings of this species with those of OrohdcUa 

 Uliitiiiani, the specimens being of equal length, the respective breadths 

 of the rings are found to be in the proportion of 2 to 8. In the head 

 region, this difference is not so obvious. 



In determining the number of rings in a complete somite, I 

 followed exactly the same method as in the last species. After open- 

 ing the animal from the dorsal surface the position of the ganglia was 

 carefully marked out by means of pins in order to ascertain which rings 

 contained them. It became very evident that one ganglion was allotted 

 to every 6 rings. The nephridial pores open on every sixth ring too. 



In colour, this leech reminds us immediately of the earth- 

 worm. The dorsal surf ice is of a reddish grey colour, sometimes vary- 

 ing to a pale blue. Near the lateral miu'gins of the body, the colour 

 becomes lighter by degrees and goes over to the pale whitish colour of 

 the ventral surf ice. There are also specimens in which the lightening 

 of the C(3lour is less gradual, so tliat the dorsal surfice looks to be of 

 the same dark colour all over except at the margins where it is whitish. 



All the specimens we have of this leech were collected at Nikkô 

 (Ijima, Nakagawa). They are found generally in localities wdiere 

 earthworms abound, and on account of similarity in colour, are very 

 liable to be mistaken for the latter. 



