JAPANESE ASTEROIDEA. 165 



not been jable to see the original description of Astrop. vapjm, 

 but it may be presumed from what we know about the descrip- 

 tions of some other species by Dujaedin and Hupe that the des- 

 cription of Astrop. vappa by these authors is a close reproduction 

 of the original of Müller and Troschel. The principal differences 

 in the descriptions of these different forms may be brought out 

 more clearly in a tabular form (p. 167). 



It will be seen from an inspection of this table that the 

 radial ratios as given by Müller and Troschel are very different 

 for Astrop. polyacanthus and armatus ; but as will be shown later 

 on, this is subject to a good deal of variation in different speci- 

 mens. The type specimen of polyacanthus apj^ears to have been 

 very large ; and although I have not seen one of equal size, it 

 appears from the table of radial ratios given below, that these 

 are, in general, larger for large individuals than for small ones, 

 so that the figures given by Müller and Troschel can not be 

 looked upon as militating against the specific identity of the two 

 species. Again, the descriptions of the adambulacral armature is 

 very different for the two species ; but it is perfectly possible that 

 the specimen of Astrop. armatus examined by Müller and Troschel 

 was not in a very good condition of preservation, so that the 

 original arrangement of the furrow spines had become obscured. 

 As to the descriptions of the armature of the inferomarginals for 

 the two species in question, the differences appear to me too 

 trifling to be considered as of specific value. Moreover, as Astrop. 

 polyacardhus is one of the commonest si3ecies of tlie genus in 

 Japan and there are no others that may possibly be confused with 

 it, I have no hesitation in concluding that Müller and Troschel 

 had this species before tliem in describing their Astrop. armatus. 



