NOTE ON A NEW DEEP-SEA EC1HUROID, PROTOBONELLIA MITSURURII, 265 



Diagnosis of the genus Protobonellia . 



Proboscis long and tubular, not bifid. Body proper with two distinct 

 ventral hooks, without anal spine. Single genital duct with a long-stalked 

 and fimbricated funnel ; anal glands once branched before ending into 

 ciliated funnels ; eggs with a nutritive cell-mass. Alimentary canal and 

 blood-vessels well developed. 



A genealogical tree of the species of Bonellidae may be constructed 

 as follows : 



/ h-otobonellia 



I . 



Bonellia Hamingia 



\ B. misakicnsis H. arctica If. sibogac 

 \B. miyajimai 



B. viridis, B. minor, />. pumicea, etc. 



In the above table, side-branches represent aberrant forms. Thus 

 aberrant Hamingia may have been derived from Protobonellia and If. sibogac 

 from a form like H. arctica. Again Boncllia misakicnsis and B. miyaji- 

 mai may be considered to be aberrant departures, as in the former the female- 

 is wholly destitute of hooks and in the latter the female is characterized of 

 supernumeral ventral hooks. 



Zoological Laboratory, 



Normal College, Hiroshima. 

 July, 1907. 



