276 BULLETIN 76, UNITED STATES NATIONAX. MUSEUM. 



Remarks. — The identification of tliis species, in view of the latitude of variation 

 of which it is capable, is a matter of difficulty and some uncertainty. I am unable 

 to decide just what to make of the several very aberrant forms listed as varieties. 

 If they are really the results of hybridism of course there is nothing gained by 

 namin" them. The species seems to be in a very unstable condition, and the extreme 

 variants might, in the opinion of some naturalists, constitute mutations (which is per- 

 haps only another way of saying that hybridization has taken place more or less 

 recently). WHiatever the cause of these variations, the fact that they exist is pain- 

 fully evident to a worker with ample material. 



HENRICIA SANGUINOLENTA ESCHRICHTH (Muller and Troschel.) 

 PI. 07, fi.tcs. 1-3; pi. 68, figs. 1-2. 



Echinasler eschrichtli Muller and Troschel, System der Asteriden, 1842, p. 25 (Greenland). — 

 Brandt, iu Middendorff's Reise in den iiussersten Norden and Osten Sibiriens, vol. 2, 

 Theil 1, 1851, pp. 32, 34 (Okhotsk Sea; var. niicrodiscus, p. 33; var. macrodiscus, p. 34). 



Cribella eschrichtii Dujardin and IIupe, Hist. nat. zoophytes Echinodermes, 1862, p. 349. 



Cribrella sanguinolenta Murdoch, Ray's Report International Polar Exp. to Point Barrow, 1885, 

 p. 159 (Point Franklin). 



Cribrella oculata Ludwig, Zool. Jahrb., Abth. f. Syst., vol. 1, 1886, p. 289 (Bering Sea; Metschig- 

 men Bay). 



Henrieia tumida Verrill, Amer. Nat., vol. 43, Sept., 1909, fig. 5 (p. 555, name only). 



Diagnosis. — Kays short and thick, rather tumid, disk large, often greatlj' arched 

 wlien animal is brootling eggs. In general appearance this species resembles a 

 short-, thick-rayed sanguinolenta abactinally, and actinally a short-, thick-rayed 

 leiyiuscula with small marginal and actinal intermediate plates and few adambulacral 

 spinelets. Abactinal and lateral pseudopaxillse small dose-set with relativel}' few 

 spinelets, and few papulaj to an area as in sanguinolenta; marginal plates in two 

 fairly regular series with few spinelets, the inferomarginal ])lates the widest ; proxi- 

 mall}' a series of smaller intermarginal plates; a series of small pseudopaxilla' 

 adjacent to adambulacrals; adanibulacrals with one furrow spinelet, and on actinal 

 surface five to seven short stubby clavate spinelets in a single zigzag series or 

 occasionally in two, decreasing in size as they recede from furrow. 



Description. — Rays five, rarel}' six. The proportions are rather variable, espe- 

 ciall}' the width of the ray at base. An average specimen from Bering Island: R = 

 32 mm., r = 12 mm., R = 2.5r; breadth of ray at base 15 mm.; an unusually slender 

 armed example: R = 29 nun., r = 8 mm., R = 3.6r; breadth of ray at base 9 mm.; 

 a remarkably thick-set specimen from Attn is nearly pentagonal; R = 14 mm., 

 r = 10 mm., R = 1.4 mm.; breadth of ray at base, 11-12.5 mm.; height of disk, 11 

 mm. (PI. 68, fig. 2.) The disk is nearly always marked by a sulcus or crease in 

 each interradius, and the rays are variously inflated or the disk is greatly arched. 

 These purely "mechanical" differences often lend a deceptive appearance to many 

 specimens. The abactinal surface may be very hard and firm or less often soft; 

 extremity of ra}' blunt. 



The abactinal skeleton is a close mesh work as in sanguinolenta, beset with very 

 slightly spaced clusters of short stubby spinelets which average a trifle shorter than 

 in Scandanavian specimens of sanguinolenta. Some examples, especially from 

 deeper water, have the s])inelets longer and more delicate than the shore forms, 



