4-So 



IF. MATSUMOTO 



Ophiodoris and the other Ophionereis, as Ophiodoris tloes between the 

 OpJiiochitoninœ and the other Ophionereidi/iœ. 



Farther, the present species reminds us of the Ophiocomidce, though 

 in a minor degree, in the wide arms and dorsal arm plates and in the 

 presence of four, instead of three, arm spines. I have already pointed 

 out that, the notched dorsal side of the vertebrae is a character of a 



different line of specialisation of the 

 Ophionereidince in contrast to the 

 Ophiocomidce, and that, the less 

 specialised forms of the Ophionerei- 

 dince in this character, such as 

 Ophiodoris, may be nearer to the 

 phylogcnetic base of the Ophiocomidœ 

 (MATSUMOTO, loc. cit., pp. 380 and 

 381). So far as this character goes, 

 the present species is also nearer to 

 the Ophiocomidœ than the other 

 Ophionereis and Ophiocrasis. 



I have observed on board the 

 " Tôkwamaru '■' that, the arms of the 

 present species are not so freely 

 mobile in life as those of Ophiocrasis 

 marktanneri, though mo: e freely so 

 than those of many other ophiurans. 

 ophionercis eurybrachiplax Clark. In alcohol, they arc rather straight 



a. From above, x 4. 6. From below, x 4. , _ 



T , , . r r ... ,. , and not so strongly Hexed as is 



<'. Lateral view 01 four arm joints near disk. J 



x4- d. Dorsal view of the skeleton of two commonly the case in the other 



oral angles and one arm base, x 7. e. Dor- _ , . . • . 



, , . ., , . Ophionereis and Ophiocrasis. lhis 



sal view 01 two vertebrae somewhat near 1 1 



disk. x6. relatively lesser flexibility of the 



arms is correlated with the very well developed dorsal arm plates, the 

 rudimentary supplementary dorsal arm plates and the not very strongly 

 notched dorsal side of the vertebrae. 



