312 



BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



The inferomarginal pseudopaxillae are not so wide as in endeca and bear fewer 

 (twelve to eighteen) coarser spinelets. The plates are only slightly wider than 

 long. Supcromarginals slightl}' larger than adjacent abactinal paxillse and about 

 one-tliird to one-half as large as the adjacent inferomarginals. There is variation 

 in the size of the superomarginals. They are about as large as the midradial paxillae. 



Actinal interradial areas tyjjically smaller than in endeca, and containing 

 fewer paxillaj sinular to those of abactinal surface, but with fewer (four to seven) 

 spinelets. A single series of paxillte extends a very short distance along free part 

 of ray (perhaps one-fifth to one-fourth length). 



Furrow spinelets two or three (only one near the end of ray), short, of the type 

 of /S. endeca. Actinal comb curved aborad at inner end, and containing six to 

 eight blunt rough-tipped spinules decreasing in length from the furrow. These 

 combs extend httle if any above the level of the marginal plates to which they are 

 adjacent throughout most of the ray. The adambulacral armature does not present 

 any very striking differences. One difference, however, is apparent though perhaps 

 not constant. In endeca the actinal comb is shghtly curved throughout its whole 

 length, but in stimpsoni it is straight on the outer part and abruptly curved at the 

 inner end. In this feature stimpsoni is intermediate between endeca and dawsoni. 



Mouth plates similar to those of endeca; marginal spinelets six to eight, the 

 inner two or three enlarged as in endeca but in extreme specimens shorter and 

 stouter. Suborals four to eight, in a single series (usually double in endeca) shorter 

 and stouter as a rule than in endeca, but not invariably so. 



Color in life: A specimen from Friday Harbor, Washington, has the center of 

 disk and a broad band proceeding thence along the middorsal region of each ray 

 leaden blue, shading to yellow ochre on interradii and rest of rays, except inner 

 half of each subambulacral comb, and mouth plates, which are like dorsum, bluish. 



Cotype. — In the Yale University Museum. 



Type-locality. — Ramsay Island, British Columbia. 



Distribution. — Southern Bering Sea (Commander Islands), and Kadiak, south 

 to Oregon, in shallow water. 



Specimens examined. — Twenty-one, from the following locahties : 



Specimens ofSolaster stimpsoni examined. 



