ASTEROIDKA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 129 



seen from the photographic figure. There is considerable variation in the density 

 and length of those spines, but they are never so long nor so robust as the supero- 

 marginals. The diflerence in size between the large and small paxilliB is better 

 marked on disk than on the nonpai)ulated area of ray. On the former area, in 

 large specimens, one may find numerous seconchirv plates, with a small central 

 spinule, in the process of forming primary plates. On the proximal half of ray are 

 from three to eight scattered pectinate pedicellarise of conspicuous size, similar to 

 the actinal pedicellariie described below. Each pedicellaria is subcircular in shape, 

 about 2.0 mm. wide, and consists of two or three primary plates juxtaposed, each 

 plate with five or six stout, curved, blunt, specialized spinules, meeting over the 

 common suture. (See figure.) Sometimes the pedicellariae lie between the upper 

 curved ends of two superomarginals. 



Marginal plates of two series, alternate. Superomarginals not encroaching 

 upon abactinal area except far along ra}'. Each plate strongly convex, almost tabu- 

 late, bearing one or two stout, movable, tapering spines, the uppernKJst the longer 

 when two are present. These spines, which form a bristling series all along ray, are 

 as long as the combined length of two superomarginals, and the base of each (or of 

 the pair) is encircled by upward of twelve or fii"teen slender auxiliary spinules. Out- 

 side of these on the sides of the eminence are numerous well-spaced spinelets, but 

 the border of the plate is naked. In this way the plates of both series have the raised 

 portions separated by naked channels. The first superomarginal spine is shorter 

 than the succeeding ones. 



luferomarginal plates wider than superomarginals, and with central portion 

 similarly elevated, this elevation having a transverse trend. Each bears a trans- 

 verse series of three (occasionally four) rigid (though movably articulated), tapering, 

 pointed, outstanding spines, subequal, or the uppermost or central the longest. 

 Usually the spines are slightly stouter and often the longest is a trifle longer than the 

 corresponding superomarginal spine. Surrounding these is a variable number of 

 auxiliary spinules, about one-third tlie length of the spines, together with scattered 

 blunt spinelets. Terminal plate small, wider than long, densely covered with spines. 



Adambulacral plates wider tlian long, with a fairly wiile suture between. Fur- 

 row margin curved, with five to seven furrow spinules, the three or four central ones 

 as long as width of plate, slender, tapering, anil blunt ; the lateralmost spinelet very 

 short as a rule. Actinal surface of plate with a transverse series of two or three long 

 terete, truncate or blunt, rather slender spines, which are nearly as Ipng as infero- 

 marginal s[)ines. On outer end of plate is often one or two much smaller sj)inules, 

 and along the adoral side of the series are a number of small papilliform or squamous 

 spinelets. In some specimens the skin covering the ])lates and spines is thicker than 

 in others. In the former the spinelets often appear to have swollen tips. 



Mouth plates spade-shaped, with broadly rounded actinostomial margin and 

 rather convex surface. Marginal spines, six to eight, either tapering or untapered 

 and blunt, the inner one or two being considerably longer than the others, which 

 diminish rapidly in size. Seven to ten spines stand on the exposed surface of each 

 plate, the outer three or four being often much smaller. The larger spines vary from 

 57444=— Bull. 76—11 9 



