IBTl i : • • 1 1 • l :\ "l NOBTB PACIFIC AND ADJACENT WATBBS li-HKK l>7 



oi average acervata ami those specimens «f pclythela with several prominent spiky 

 Bpines in s group, or s single Bpine bui rounded by enlarged mm ondary Bpini b, at show d 

 mi Plate 38, Figu A speoimeii with R 82 nun., r is nun K i .". i ha 



following Features: 



Abactinal spines, as the plates, are of two very diver ■ ire about 



three longitudinal series, quite irregular, hut in other specimens sometimes Fairly 

 regular, of Bpaced heaps <>f capitate spines with Bwollen oblate hemispherical, sul>- 

 lt I « > ' > < > - < ■ . ovate (or in other specimens even acorn-shaped) vertically Btriated tips. 

 The centra] Bpine is much tin- Largest of any of the !_-it >u [>. while the Bubsidiary mem- 

 bers, unequal in size, form a circle or irregular group around it. The diameter "f the 

 largest spines is about L.5 nun. and iliat of tin- smaller 0.4 to 0.76 mm Scattered 

 closely over the abactinal Burface in irregular lines, rather vaguely defining a reti- 

 culum, are numerous usually unequal small Bpinelete (0.4 to 0.6 nun diami 

 which duplicate in miniature the form and sculpturing of the aeervate spines .lust 

 above the Buperomarginala is a cone variable in width, rather free from Bpinelete and 

 filled with numerous lanceolate, blunt, straight pedicellariae about 0.5 mm, 

 These are sometimes incipiently toothed. Smaller ones are scattered over the dorsal 



surface. The spine- are surrounded by small Crossed pedicellariae in one ur t \\ ■ • 



circles, the interstices between the Bpines of the groups being filled with them. In 

 alcoholic specimens the pedicellariae seem to arise from cushions of tissue surrounding 

 the Bpines and 9pinelets, and have the appearance of being everywhere numerous. 

 In large specimens there may be three tiers around the Bpines 



Superomargina] Bpines verj variable in Length and caliber, but slenderer and 

 Bometimee larger than the major dorsal spines. In the type Bubforma each plate has 

 one Bpine except the distals which sometdnee have two. The Bpines are blunt, cylin- 

 drical-clavate, faintly striated longitudinally and the tips are often compr es sed 



Other variations have two and even three Bpines in BUCh oases -mailer than when 

 one i- present on the proximal plates and three and four on the distal for example 

 another larger specimen from station 3247, one from stations 

 Bee variations). In such specimens the abactinal aeervate spine- form usually 

 more rounded heaps, without a verj prominent central member, hut tin- is not 

 invariable (as stations 3233, 3274 



The type Bubforma has a row of inferomarginal spines >imilar to but longer and 

 heavier than the Buperomarginals, and a series of actinala similar to but a little 

 smaller than the inieromarginals. Other varieties have two equal or unequal infero- 

 marginala, and two -erics <,f actinals, the same specimens having also two or even 

 three Buperomarginala pxoximallj Set variation- The superomarginal Bpines 



have B den-.' wreath of about three tiers of Crossed pedicellariae. while the infer. i- 



marginal and actinal spines have thick clusters «'U the outer face In the type 

 Bubforma the intermarginal channel, owing to the single row of Buperomarginal and 

 inferomarginal spines, is conspicuous < bui it is practically obliterated in varieties w ith 

 multiple rows "f marginal Bpines) and is armed with lanceolate hlunt pedicellariae, 

 A- might he expected, when there i- little stabilitj in the number of marginal 

 Bpines, the adambulacrals are variable. In the type subforma the -pine-, most 

 commonly alternate two and one. the furrow Bpine of alternate plates being more 

 advanced on the furrow face of the plate, as in typical I although not so far). 



