1 20 VERRILL 



Dorsal spines not numerous, conical, relatively stout, usually stand- 

 ing singly, one to an ossicle, and forming three or five rather irregu- 

 lar rows. Ocular plate relatively large, bearing a dense cluster of 

 small spines. Minor pedicellariae of unusually large size and with 

 strongly curved blades are usually numerous in groups around the 

 dorsal spines and on the papular areas. Adambulacral spines mostly 

 two to a plate, or alternately one and two distally, very slender, 

 terete, often slightly clavate. Lower marginal spines, which are much 

 larger, acute, conical, like the dorsals, but longer, form a single row 

 next the adambulacrals, or there may be two to a plate, proximally, 

 in the larger specimens. The synactinal plates appear to be few 

 and small, or altogether lacking in our examples, but may occur in 

 larger ones. Upper marginal spines form a single row and resemble 

 the dorsals in form and size. Major pedicellariae few, small, ovate. 



The ambulacral feet are in four rows, but the adjacent rows form 

 only a zigzag line, so that they sometimes appear almost biserial. 



This species looks very much like a Pedicellaster, not only in size 

 and spinulation, but also in the character of the pedicellariae. The 

 arrangement of the ainbulacral feet in four rather indistinct rows 

 forbids its place in that genus, however. 



Our specimens are evidently not full-grown, but it probably never 

 becomes large, perhaps not more than 50 mm. in diameter. 



Virgin Bay, Alaska (W. R. Coe). 



It is more delicate than the Atlantic L. tenera, of the same size, 

 but has larger dorsal spines, much fewer in number, and the dorsal 

 pedicellariae are much larger and diflferent in form. The much 

 smaller number, larger size, and isolated position of the dorsal spines 

 indicate that it cannot be the young of C. cribraria or L. hexactis. 

 The young of the latter, of similar size, are known to me, and are 

 very different. 



LEPTASTERIAS ARCTICA (Murdoch). 



Plate LVi, figures i, 2 (young) ; plate lxxi, figures i, 2; plate Lxxn, figure i; 

 plate Lxxxui, figures 2, 2a (details). 



Asierias arctica (Murdoch), Report of the International Polar Expedition 

 to Point Barrow, Alaska, under Lieut. Ray, 1885, p. 159. 



Mr. Murdoch's original description is as follows: 



" Rays five, rounded above, elongated, tapering regularly to the 



tips. Radii as i : 3.5. Disk small, its radius about equal to width 



of ray at base. Interambulacral spines round and slender, with 



rounded tips, usually two to each plate. No small spines between 



