l82 VERRILL 



ray, usually bears a single acute spine, though on the distal part each 

 bears two divergent spines, of which the inner is much smaller and 

 shorter. But in the present species there are two nearly equal, long, 

 slender adambulacral spines to each plate proximally as well as 

 distally. 



Another arctic species (U. pcmopla Stuxberg) 1 from Spitzbergen, 

 etc., has more resemblance, for it has few dorsal spines and abundant 

 dorsal groups of minor pedicellariae. But these pedicellariae are not 

 of the same form and are much smaller, as also the major pedicel- 

 lariae. Its ventral spines are much more numerous, longer and more 

 slender. 



ORTHASTERIAS LEPTOLENA Verrill, sp. nov. 



Plate LXIV, figures i, la, 2, 20 (ventral and dorsal sides of types) ; plate 

 LXXVII, figures 2, a-d (pedicellariae). 



The disk is small; the rays five, long, slender, tapered, well 

 rounded. The radii of the larger (No. i8a) are 7 mm. and 76 mm. ; 

 ratio, nearly i : n. The smaller has radii of 4 mm. and 44 mm.; 

 ratio, i: ii. 



The dorsal spines of the rays and disk are rather long and of 

 nearly uniform size and length, numerous but not crowded, mostly 

 one to a plate, and pretty uniformly distributed, nearly in quincunx, 

 or in five indistinct, alternating rows on the rays, the median row not 

 differing from the rest. These spines are tapered, but obtuse and 

 rough or subsulcate at the tips, which are often flattened. Between 

 them there are large, denticulate dermal pedicellarise, often about 

 half as thick as the spines. Papular areas are large; the papulae 

 small and numerous. 



The superomarginal spines form a single regular row, one to all 

 plates. They are similar to the dorsals in size and form. The infero- 

 marginals form a very distinct double row, two to a plate, sepa- 

 rated from the upper ones by a rather deep naked channel, with 

 large papular pores. The inferomarginal spines are like the upper 

 ones in form, but a little longer and less tapered, obtuse. There are 

 no spiniferous interactinal plates. The peractinal row is represented 

 by a proximal row of small, narrow, spineless plates, five to ten in 

 number, on the different rays, and joined closely to the adambulacrals. 

 In the smaller specimen these actinal ossicles are rudimentary or 

 lacking. 



1 See Doderlein, 1900, p. 204, pi. iv, fig. 2 ; pi. v, figs. I, 2. 



