SHALLOW-WATER STARFISHES 169 



The radii are 18.5 mm. and 157 mm.; ratio, about i : 8.5. The disk 

 is small, the five arms are long, rounded or subangular above, and 

 taper very gradually to rather small tips. The dorsal plates are 

 numerous, forming five rows, with some interpolated ones. They 

 are large, wide, considerably thickened or convex, those in the three 

 primary radial rows having more convex centers and forming a 

 low but distinct carina. 



The dorsal spines form about five more or less regular rows above 

 the upper marginals, often with some intermediate ones. The five 

 main rows extend nearly to the tips of the rays, the spines becoming 

 rather crowded distally, while proximally they stand well apart, 

 except in the median row. The dorsal spines are all nearly equal, 

 except distally, rather large, cylindrical, or slightly clavate, with 

 obtuse or rounded sulcate tips, and bearing dense wreaths of minor 

 pedicellariae above or about the middle. 



The larger spines are about 4 mm. high and i mm. in diameter. 

 The upper marginal plates are also thick and convex; their spines 

 are like the dorsals, though a little larger, and bear similar groups 

 of pedicellariae. They form a very regular row, one to each alternate 

 plate. Along the middle of the ray they stand about 3.5 mm. to 4.5 mm. 

 apart, but become crowded to i mm. or 2 mm. distally. Between the 

 upper and lower marginals there is a rather wide naked channel, 

 crossed by the thickened descending apophyses of the marginal plates, 

 and bearing on the plates many very large, ovate and spatulate major 

 pedicellariae. These often alternate with the spines; others are 

 irregularly placed. 



The inferomarginal spines form two rows, two divergent spines 

 standing obliquely close together on most of the plates. They are 

 similar to the upper ones in size and shape, though many are a little 

 compressed and more strongly sulcate at the tips. They bear large 

 groups of minor pedicellariae on their upper sides, about mid-height. 

 The inferomarginal plates are strongly convex, with the outer sur- 

 face elliptical. Another regular row of similar spines is borne by 

 the peractinal plates, close to the adambulacrals, each corresponding 

 to about five pairs of the latter. They extend regularly nearly to 

 the tips of the rays and have papular pores between them. The per- 

 actinal plates are rounded and convex. 



The adambulacral spines form two very regular and equal rows. 

 They are slender, scarcely tapered, terete, or slightly compressed 

 distally, with blunt tips. They are shorter and much smaller than the 

 adjacent actinal spines. Those on the adoral plates are distinctly 



