ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS— FISHER 141 



broad end terminating in two or three unequal, almost malformed tips. (PI. 67, 

 fig. 7a, 7b, station 3466.) Beyond the basal third or half of ray (and throughout in 

 medium-sized and small specimens) the spines are slenderer, tapered and blunt, the 

 outer being frequently variably compressed, and all three, or only the outer one or 

 two, rather faintly channeled. 



Adambulacral spines two, slender, blunt, or truncate, sometimes tapered 

 slightly, sometimes untapered, only slightly shorter but very much slenderer than 

 the actinal spine. The spines are usually compressed and form two very regular, 

 not very divergent series; and the spines on the adoral carina and succeeding plates 

 are longer than the rest. The largest specimen (pi. 64, fig. 3; pi. 68, fig. 1), from 

 station 3466, 56 fathoms off Washington (R 300 mm.) has the proximal spines with 

 a sulcus at the tip. This is the same example in which the inferomarginals are mod- 

 ified. There are 30 to 36 adambulacral plates to 10 inferomarginals at basal third of 

 ray. 



Adoral carina somewhat narrowed behind the mouth plates and composed of 

 three to five pairs of contiguous adambulacral plates, each bearing a spine which is 

 slightly longer than those a dozen plates farther along the ray. The actinostome is 

 sunken and the oral plates are not superficially visible. The latter are bent down- 

 ward somewhat as viewed from below, and bear a small spine on the actinostomial 

 margin directed over the mouth of the furrow close to the nerve cord, and another 

 (less often two) adjacent to inner end of median suture. The latter spine is usually 

 flattened, blunt, or truncate, a trifle curved and rarely spatulate. There is generally 

 one, sometimes two, suboral spines similar to the succeeding adambulacral spines. 

 These all form a very bristling armature over the mouth and are noticeably longer 

 than the spines a little farther along the ray. (PL 65, fig. 9.) 



The skeleton is unusually stout and close-knit so that the papular areas are 

 small. (PL 67, figs. 1, la.) The primary plates are four-lobed and convex and the 

 carinals and marginals are very strongly imbricated. The carinal series is not straight 

 in grown specimens. The dorsolateral plates are very irregularly arranged and are 

 connected with one another and with the carinals and superomarginals by -irregular 

 elliptical or oval secondary ossicles. The ventral apophysis of the superomarginal 

 plates is comparatively short, and the face of the plate lacks a specialized area of 

 hyaline beads (except in very young specimens). The actinal plates arc pretty 

 regularly opposite each inferomarginal and are separated from ono another by a space 

 equal to their own size, or somewhat less. 



Papulae three to five to an area, or as high as nine in the largest specimen. There 

 is a definite series of actinal papulae alternating with the actinal plates and two or 

 three to an area. In living specimens the papulae are conspicuous. 



Madreporic body large, flat, with fine radiating striae. 



Straight pedicellariae, greatly variable in numbers, are scattered ovor the abac- 

 tinal surface among the spines, along the intermarginal channel, among tho actinal 

 spines, and on the margin of the ambulacral groove. The larger ones of the supero- 

 marginal and abactinal plates are usually rather acute-ovate as viewed from the 

 side and narrowly or broadly spatulate (with two to four curved short teeth which 

 interlock) seen frontwise. There are also smaller ones which arc lanceolate, acute, 

 and without teeth. The largest unguiculatc pedicellariae may equal 2 mm. in length. 

 Those of the adambulacral plates vary greatly in size. They arc usually borno on 

 64406—28 10 



