2S0 ASAJIRO OKA ; ON SOME NEW 



surface is the darkest. The dorsal surface is divided indistinctly into 

 three longitudinal areas, one brond median and two narrow lateral. 

 The lateral areas, as well as the whole ventral surface, are of a pale 

 oranfj-e colour. The median area of the dorsal surface is of diiferetit 



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colours according to the species, and also even to the individual 

 (olive green, grayish, l)luish red). 



The land-leeches of the genus Orohdella are found in various 

 mountainous ])arts of Japan. 'Jlie localities, where the specimens in 

 my collection come from, are Kioto, Gifu, Flakone, Nikko, and Kibö- 

 zan near Kumamoto. They are found crawling under moss and fallen 

 leaves or in moist earth, in the same manner as earthworms, which 

 constitute tlie chief source of their noin-isliinent. Being possessed of 

 no jaws these leeches have no ])ower of Ijiting and consequently of 

 sucking blood. They go about in pursuit of earthworms and swallow 

 them entire, as I have repeatedly found by dissection. My sections 

 of these leeclies show sometimes the peculiarity of presenting the 

 structure of tw(3 worms at once, that of the leech and that of the earth- 

 worm swallowed. With regard to haljits, therefore, Uvolnldla has 

 almost nothing in common with Ha')ii(idtps((, but rather resembles 

 Ci/licohdell'i and Lumhricohdella. 



The Orohddlœ are pretty large leeches, most of the specimens 

 that were found mature being more than 10 cm in length. Among 

 the collection there is an extraordinary large one preserved in alcohol 

 that measures UK^re than 27 cm. 



Before proceeding to the description of the individual species, I 

 may here say somethiiig aI)ont the methods followed by different 

 authors in counting tlie rings and determining the boundary of the 

 somites. According to the method proposed ])y Whitman (1<S,S4), the 

 ring's are counted on the dorsal surface, be^'innino- with the first ociili- 

 ferons ring. This is certaiidy very sim{)le, and has hitherto been 



