JAPANESE ASTEEOEDEA. 449 



Ahactinal skeleton. — The most prominent feature of the dorsal 

 side is the presence of a carinal row of conical or ellipsoidal 

 tubercles in each arm and a conspicuously large, ellipsoidal tuber- 

 cle in each radius of the disk, the latter together enclosing a 

 rather small central area. These adcentral tubercles have per- 

 fectly rounded or even flattened tops and are entirely covered 

 over with flattened, polygonal granules, which are so closely set 

 as to impart a smooth appearance to the tubercles. One or more 

 of the granules at the top are sometimes larger and more elevated 

 than the surrounding ones, hence it is possible that in some speci- 

 mens there may be one or more spines at the top of these 

 adcentral tubercles. On the outer side of each adcentral tubercle, 

 close to it, there is a pair of smaller, conical tubercles, nearly as 

 large as the last or the penultimate tubercle of the arms, covered 

 over with polygonal granules and with a short, blunt, conical, 

 immovable spine at the tip. In two of the interradii in my speci- 

 men, one member of the pair is wanting. The tubercles of the 

 arms are conical in form, and gradually decrease in size towards 

 the tip, there being usually five to seven of them in each arm. 

 They are tipped with a blunt, conical immovable spine, which is, 

 however, usually absent from the small terminal tubercle. Irre- 

 gularities in the relative size of these tubercles may also be 

 observed. Between these tubercles there are low rounded plates. 

 The central area enclosed by the five adcentral tubercles is 

 bounded by elongated ossicles stretching between the tubercles and 

 forming the sides of a regular pentagon ; tliis pentagon is again 



divided into five equal triangular areas by as many depressed 

 ridges radiating from the centre to each tubercle. 



, - On either side of the lophial, or carinal tubercles, there may 



