JAPANESE LAND LEECHES. 288 



There are in my collection IS specimens of this leech, of which 

 14 are adults. The dimensions of the three largest specimens are as 

 follows : 



Leni>'th, 107 mm. 103 mm. SO mm. 



Width, 11mm. 10 mm. 7.5 mm. 



Depth, H.5 mm. (î.ô mm. H.5 mm. 



In smaller specimens, the difference between the two hist dimen- 

 sions is less obvious, so that their body has exactly the same form 

 as the earthworm. 



Of the external rinas, the ord and the last rings present pecu- 

 liarities, in so far as the former is divided on the dorsal surface bv a 

 furrow into two unequal parts, and the latter is distinct only on the 

 dorsal side. On passing over to the ventral surface, the last ring 

 enters into the formation of the acetabulum, so that, if counted on the 

 ventral side, the latter organ comes next to the penultiinate ring. 



As concerns the colour, this species exhibits great variability. 

 While the larger specimens obtained from Kioto are decidedly greenish 

 on the dorsal side, as sliown in the Fig. 1 (PI. XXVIII), all the 

 smaller ones from various othei- localities are of a bluish-red colour. 

 There are still others, whose dorsal surface is brownish or greyish. 



There being no segmental papilla?, which distinguish some of the 

 rings from the rest and are of great use in determinino- the boundarv of 

 the somites, we have no other method of counting the somites than bv 

 examining the intemnl organs. As already noticed, I began by ascer- 

 taining the topographical relation of the external rings to the nervous 

 ganglia, which exhibit the metameric arrangement more regularly 

 than any other organ. There are in this species, as in all other known 

 Hinidinea, twenty one ventral ganglia, not counting the oesophageal 

 and the acetabular ganglionic masses. A median longitudinal section 

 of the whole animal hardened in alcohol shows most clearly, that, of 



