ASTEROIDEA OF NORTH PACIFIC AND .ADJACENT WATERS FISH El!. 309 



Ahactinal surface. — Abactinal pseuflopaxillse typically vt'iy small and crowded. 

 Specimens from 2S.t1 and 4246 are exactly matched by an example from off Cupe 

 Cod. There is less difference between these than between two Cape Cod examples, 

 or between the latter and a Swedish specimen. In large Pacific specimens the 

 spinelets of proximal midradial paxilhc vary from five to about nine or ten. In the 

 Swedish example there are commonly as many as nine, less often ten, and as few a.s 

 three or four spinelets. The paxillse on sides of rays are usually very slightly larger 

 than those of the mitlradial regions and center of disk. 



Marginal flates. — In the original descrijition of S. gakmdes: "The marginal 

 spines are about as in 8. endeca, but the inferomarginals are more elongated trans- 

 versely, and bear a decidedh' greater number of more minute sj)inules." The 

 available specimens have been examined with reference to this character. In two 

 equal-sized examples, one from off the Shumagin Islands and one from off Cape Cod, 

 the inferomarginals are the same size, or if anything a little larger in tiie latter (that 

 is, more elongated transverseh'). An average plate in the Aljiskan example bears 

 thirty-three spinelets, while a corresponding ])Iate in the Atlantic s])ecimen has 

 thirty-one, and in the Swedish example thirty-two; neighboring plates in all three 

 specimens vary three to eight on either side of these figures. Some of the specimens 

 from 4246 have the inferomarginals decidedly nan-ower transversely than any of the 

 above examjiles; while among all the available material none can be said to have 

 the inferomarginals more elongated transversely. The characteristic is evidently 

 individual and not specific. Again comparing the spinelets for size, we find varia- 

 tion in both Atlantic and Pacific material; the Shumagin Islands example (several 

 times referred to) has coarser spinelets than Atlantic specimens. Specimens from 

 4246 {"S. galaxides") have the spinelets variable, some slightly finer, some identical, 

 some slightly coarser than the Cape Cod material. The differences in the infero- 

 marginals of Atlantic and Pacific specimens are no greater than between different 

 individuals from the same locality, or from different localities of the same ocean. 



The superomarginals are somewhat more conspicuous than the immediately 

 adjacent abactinal pseudopaxilhc, carrying twelve to fifteen spinelets near the base 

 of ray. They vary in size with the inferomarginals, and as in Atlantic specmiens, 

 are sometimes opposite the interspace between two inferomarginals, or else directly 

 above and close to the latter. In shape they are roundish, irregular, or less often 

 subquadrate. 



Adinal irUerradial areas. — In the description of S. galaxides: "The synactinal 

 series of pseudopaxillas extends only to about the basal tliird of the free part of the 

 ray. They are relatively smaller than in endeca, being here only about half size of 

 the inferomarginals proximally. The actinal interradial areas are aj^parently rela- 

 tively larger than in endeca and bear a larger number of compressed pseudopaxilhv, 

 the larger ones similar to the inferomarginals and synactinals." 



The size of the actinal interradial areas depends upon tiie number of rays and 

 breadth of disk, and w hile it is j)ossible, by comparing small liisked Atlantic endeca 

 with larger disked Pacific examples, to fiml larger interradial areas in the latter, it is 

 also true that a reverse j)rocess will reveree the results. As a matter of fact, there is 

 certainly too little difference to be of importance. In the Shumagin Island example 



