17S BULLETIN 76, VNITED STATES NATIONAL MUSE! "M 



space between the spines may reach 10 or 12 mm. The spines are strongly capitate, 

 robust, with ornately grooved, subglobular to acorn-shaped ends, and are seated 

 rigidly on convex plates of the very irregular skeleton. The dorsolaterals are some- 

 limcs heavier than the earinals and superomarginals, sometimes subequal to them. 

 (PI. 77, fig. 4.) In between the spines are conspicuous clusters of papulae guarded by 

 small lanceolate pedicellariae, attached to the papulae, and in most cases by few to 

 many much larger stone-hammer denticulate straight pedicellariae similar to those of 

 giganteus. There arc very few isolated clusters of crossed and furcate pedicellariae 

 among the papulae. 



The other extreme has narrower rays and more numerous, generally slenderer 

 sometimes quite unequal abactinal spines. There is little to distinguish it from 

 some specimens of true giganteus (with which Verrill confused it) except the characters 

 of the pedicellariae enumerated in the diagnosis. One may count from 9 to 15 

 spines across the ray between the two superomarginal series, but there is never 

 regular serial alignment. The collar of blue skin around each spine is generally 

 narrower than in the type forma. The usually slenderer rays cause the spines to be 

 less widely spaced. There is complete intergradation between the two formae in a 

 good series of large specimens from Venice, Calif., contributed by Prof. A. B. Ulrey. 

 The Laguna Beach specimens are all the type form. 



The superomarginal spines are similar to the dorsals, but generally more numerous 

 than the outer dorsolaterals, and form a straight series, low on the side of ray. A 

 specimen from San Diego has 23 superomarginal spines corresponding to 47 infero- 

 marginal plates. 



Inferomarginal spines smaller than the superomarginals, two to a plate, sub- 

 clavate, finely grooved and with a well marked, external, often deep sulcus. There 

 are usually two or three longiseries of actinal spines similar and subequal to the in- 

 feromarginals, sometimes a little heavier on the proximal part of the ray. They all 

 carry external clusters of crossed pedicellariae. As in typical giganteus certain speci- 

 mens, on some of the inferomarginal and actinal plates of the proximal half of ray have 

 two to four spines, greatly increasing the spine count and destroying any regular 

 alignment. Such a specimen may have 8 or 10 spines in an irregular transverse series. 



Adambulacral spines slender, flattened, subtruncate or blunt, slightly tapered or 

 not, sometimes with a shallow groove on the outer half, deepening toward the tip 

 (Laguna Beach). In such a specimen the spines range from slightly tapered, blunt, 

 to slightly spatulate. The adoral carina is very narrow, composed of about 10 or 12 

 pairs of plates, and back of the mouth plates the first two or three pairs of plates 

 have the spines in single file (some of the spines being suppressed). 



Each mouth plate has two actinostomial spines (the latter quite small) and one 

 suboral, tapered and pointed, similar to but often stouter than the adjacent adam- 

 bulacral spines. 



Crossed pedicellariae in circumspinal wreaths abactinally and in clusters on 

 outer side of inferomarginal and actinal spines. They are less numerous than in 

 typical giganteus which sometimes has clusters between the spines. Pedicellariae 

 average larger than in giganteus; length 0.5 to 0.46 mm. (Laguna Beach; San Diego; 

 Lower California). (Compare pi. 73, figs. 5 and 6.) In form they adhere closely to 

 the generic type and are very little different from those of giganteus. Note relative 



