JAPANESE ASTEEOIDEA. 



195 



This is a very well defined species with prominent charac- 

 teristics, and in certain localities nearly as common as Astrop. 

 scoparius. Some of the characters are fairly variable, and this fact 

 should be borne in mind in the determination of the species. The 

 body is very flat, and is of a greyish brown colour on the upper side. 



Radial ratio. — So far as I have observed, the radial ratio does 

 not appear to be so variable as in some other species, as may be 

 seen from the following table. It may also be remarked that this 

 ratio is more constant in relation to the size of the specimens. 



