MONOGRAPH OF JAPANESE OPHIUROIDEA. 



157 



disk diameter and 20 mm. in the arm length. With the excep- 

 tion of three which are five- armed, they are all six-armed. One 

 of the five-armed specimens has three larger and two smaller 

 arms, while another 

 has tw^o larger and 

 three smaller ones. 



The ventral arm 

 plates have each an 

 hour-glass shaped 

 depression on the 

 surface, which seems 

 to me to be a dis- 

 tinctive character of 

 this species, though 

 apparently unnoticed 

 by previous authors. 

 In Dödeklein's 



photograph, this de- 

 pression is faintly 

 visible. 



Colour in al- 

 cohol : dull green ; 

 disk with two or 

 three patches of very 

 dark green ; arms 

 banded, two darker 

 joints alternating 



with four or fi\'e lighter ones ; each dorsal arm plate with three 

 yellowish spots on the outer margin. 



Fig. 38. OiMadis moclesta. x20. a. From above. ?;. From 

 below, c. Side view of three arm joints near disk. 



