JAPANESE ASTEROIDEA. 169 



certain cases a tendency to hold by the same ratio may be 

 detected in specimens from the same locality, it appears that this 

 is more a matter of individual variation than a geographical habitus. 

 Superomarginals. — As may be seen from the foregoing table, 

 the number of superomarginals is not necessarily proportional to 

 the radial ratio, i.e., individuals with relatively large R do not 

 always have more superomarginals. The most prominent feature 

 of this species is the presence of a large, prominent, conical spine 

 on the abactinal surface of the superomarginals (PI. Ill, fig. 42, 47, 

 48). The series begins with the first superomarginal, which is 

 usually more prominent than the others and bears an especially 

 large spine. The next two or three are usually without spines, 

 but it appears from the statements of previous observers that 

 these also may be armed with spines, although I have not seen 

 a specimen, in which the series of the superomarginal spines is 

 continuous throughout. The following variations have, however, 

 been observed. These formulaß are written so that the figures show 

 the ordinal numbers of the unarmed superomarginals, the first set 

 representing the madreporic interradius, and the following the other 

 interradii in counter-clockwise order, the dash the interradial line. 

 Specim. A 3. 2.-2. 3., 3. 2.-2. 3., 4. 3. 2.-2. 3., 3. 2.,— 2. 3., 



3. 2.-2. 3. 



8pecim. B 4. 3. 2.-2. 3. 4., 4. 3. 2.-2. 3. 4., 4. 3. 2.-2. 3. 4., 



4. 3. 2.-2. 3., 4. 3. 2.-2. 3. 4. 



Specim. C 4. 3. 2.-2. 3., 3. 2.-2. 3. 4., 4. 3. 2.-2.3., 



3. 2.-2. 3. 4, 4. 3. 2.-2. 3. 4. 



Specim. D 3. 2.-2. 3. 4., 4. 3. 2.-2. 3. 4., 3. 2.-2. 3. 4., 



4. 3. 2.-2. 3. 4., 4. 3. 2.-2. 3. 



Specim. E 3. 2.-2. 3., 3. 2.-2. 3., 3. 2.-2. 3., 3. 2.-2. 3., 



9 Q 



