JAPANESE ASTEEOIDEA. 



167 



and as it accords very well with the description of Astrop. 

 polijacanthus we may follow previous authors in uniting the two 

 species. As for Astrop. hi/strix, the question turns on the presence 

 or absence of unarmed superomarginals next to the prominent 

 interbrachial pair ; but this has already been shown by previous 

 observers to be subject to variation, and we shall see more of it later. 



Basing my observations on a goodly number of specimens 

 from diflerent localities, I may give the following description of 

 this species. 



Radial ratio. — This is best seen from the following table. 



