122 VERRILL 



of small or moderate size, have only very small clusters of pedicel- 

 lariae, and these may be seen only at the base of the spines, espe- 

 cially when dry, the sheath being rudimentary or contracted ; or they 

 may be lacking on many of the spines in young specimens. 



The superomarginal spines are much like the dorsals in size and 

 form, and therefore not easily distinguished in many specimens, but 

 they are usually slightly longer. In most specimens of average size 

 there is a short proximal row of more slender spines interpolated 

 between the upper and lower marginals. 



The inf eromarginal spines are decidedly longer and larger than the 

 upper ones, often being twice as stout. They are usually terete, 

 scarcely tapered, often slightly curved and obtuse. Frequently they 

 stand two to a plate ; the upper ones are smaller ; but in many cases 

 they stand singly, in a regular row. The larger specimens usually 

 have a short proximal row of interactinal spines, similar to the 

 inferomarginals. This is true of the larger of Mr. Murdoch's type- 

 specimens. The adambulacral spines stand one or two to a plate in 

 irregular alternation. They are nearly as long as the inferomarginals, 

 usually much more slender, terete and blunt, sometimes slightly 

 clavate, but in some cases they are stouter than usual and nearly as 

 large as the inferomarginals. They usually bear clusters of minor 

 pedicellariae, and many isolated major pedicellarise. 



The apical peroral spines are usually rather large and strong, 

 being considerably stouter than the adorals. The epiorals are also 

 rather stout and distinctly longer than the adorals. 



Major pedicellariae are sometimes few in number, but usually there 

 are many of rather small size attached within the margin of the 

 grooves, and some of larger sizes on and between the adambulacral 

 spines and oral spines. Some of the larger kind also occur on the 

 interradial areas and lateral channels. They are mostly compressed, 

 ovate-lanceolate or oblong-lanceolate, with acuminate tips. The 

 larger ones are often as stout as the adjacent adambulacral spines, 

 and these usually have dentate tips. 



Mr. Murdoch described the same specimens, as preserved in 

 alcohol, hence he overlooked some of the details, obvious when dry. 



Two young specimens, which I refer doubtfully to this species, 

 were collected by Dr. W. H. Dall on the coast of East Siberia, at 

 East Cape (U. S. Nat. Mus., No. 6031). 



Others, similar, were collected in Bering Strait by Robt. White 

 (No. 16591. PI. LVI. figs, i, 2.) The radii of the largest are 

 3.5 mm. and n mm. The dorsal spines are small, clavate, arranged 



