166 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



summit of the higher ridges, above this closely packed mass of papulae and pedicell- 

 ariae, arc the stout small spines with subglobose striate ends (pi. 75, figs. 5a) arranged 

 usually in single file, sometimes by twos on the carinal series, or forming small groups 

 at the nodes. These tubercles are usually nearly uniform but variations occur in 

 which there is considerable disparity in size. 



The variations in the pattern formed by the abactinal spines are as numerous 

 as the individuals of the species, typical examples being figured. 



The superomarginal spines are not different from the abactinal though occa- 

 sionally a little larger than those directly above them. The plates carry usually one 

 spine, sometimes two, especially at nodes. Some variations have a considerable num- 

 ber of the plates with two marginal spines, or one accompanied by two smaller spine- 

 let s. A feu accessory spinlcts appear sometimes on the intermarginal plates. 



Inferomarginal plates with usually two spines in an oblique series, with upward 

 of six similar actinal spines between them and the adambulacral system. Actinal 

 spines one to a plate These spines are longer and more clavate than the abactinal, 

 the ornate fluting being interrupted on the outer side for the attachment of a dense 

 cluster <>(' crossed pedicellariae. The actinal armature is dense and efficient. In life 

 very long slender pointed papulae extend far beyond the spine tips, to such an extent 

 as to nearly hide the armature on the proximal part of the ray. 



Adambulacral plates inconspicuous, narrow, with a single slender, tapering, blunt, 

 terete or flattened spinelet. The spinelets are fairly regular, very closely placed, 

 about as long as the inner actinals and they increase in length over the area where the 

 furrow is broadened, at base of ray, to decrease again on the long adoral carina. 



The adoral carina along its inner half is narrower than the mouth plates and is 

 composed of upward of 10 pairs of plates. It bends downward (as viewed from the 

 oral surface) to the oral angle. (PI. 75, fig. 2.) The very small actinostome is guarded 

 by the stout tapering oral spines, which are stouter than the adjacent adoral spines. 

 One or tw 7 stand on the free margin and a longer suboral on the middle of the surface. 

 (PI. 75, fig. 2 ; pi. 79, fig. 1.) Less often there are three flattend actinostomial spinules. 

 Length and thickness is extremely fariable even in specimens from the same region. 



Crossed pedicellariae (pi. 73, figs. 1, la) : Abundant, mixed in varying proportions 

 with furcate straight, on abactinal plates and, practically without furcate straight, in 

 dense clusters on inferomarginal and actinal spines. They are smaller than in typical 

 nodijerus being 0.27 mm. long but differ in no important details (Sitka, Monterey). 



Straight podicellaiiae: (a) The characteristic Pisaster bifid furcate pedicellariae 

 are very numerous abactinally, and sometimes intermargrnally. Clusters composed 

 almost entirely of them are found in the bottom of the hollows among the abactinal 

 papulae. Near the bases of the spines they accompany the crossed form. They 

 measure 0.27 mm. broad by 0.22 high (Sitka); 0.25 by 0.25 mm; 0.29 by 0.3 (Monterey) 

 (PL 74, fig. 2; pi. 79, fig. 6.) 



(b) Undifferentiated lanceolate, of very small size (many as small as 0.13 mm. 

 long), are scattered over all the papular areas. These are similar to Plate 76, Figure 

 6a. Clusters of tiny lanceolate pedicellariae surroundinga large one, at the endof long 

 peduncles, are distributed all along the furrow face of the adambulacral plates — not 

 on all the plates, but here and there. (PI. 76, figs. 6, 6a.) In some dried specimens 

 tl'oso appear, superficially, to be attached to the furrow spines. In no instance has 



