NEW STARFISHES FROM DEEP WATKK OFF CALIFORNIA AND ALASKA. 295 



Family ASTROPECTINIDjE Gray, 1840. 



Genus BATHYBIASTER Danielssen & Koren. 



Bathybiaster Danielssen & Koren, X> 1 Magaz. for Naturvidensk, XXY1I. I, 1883,285; Den Norske Nordhavs-Exped n, 



1876-78, Zoologi, XI. Asteroidea, 1884, 94. 



Bathybiaster pectinatus, new apecies. 



Rays 5. R = 73mm.; r = 15.5 mm. R = 4.7r. Breadth of ray at base, between first and second 

 superomarginals, 1(5 mm.; midway along ray, 13.5 mm. 



Rays moderately elongate, tapering continuously from base to a sharply pointed extremity; inter- 

 brachial angles rounded; lateral walls nearly vertical, high; abactinal surface slightly inflated on disk, 

 otherwise plane; actinal surface convex on rays; a low epiproctal elevation. 



1 'axilla- of abactinal area small, not crowded except at center of disk; arranged in transverse rows 

 at sides of paxillararea of rays; no definite arrangement along median radial line; size decreasing 

 toward ends of rays, and at center of disk, largest paxilla on disk midway to margin, each consisting 

 of M or 4 centrally situated, small, cylindrical, round-tipped, membrane-invested spinelets, surrounded 

 by a peripheral series of 10 or 12 slightly slenderer ones, the whole forming a very compact, flat-topped, 

 subcircular, or irregularly elliptical group; small papillae readily seen in the spaces between the 

 paxilla-, especially on the rays. • 



Superomarginal plates, 46 in number from median interradial line to extremity of ray, encroach- 

 ing but slightly upon abactinal area, short, high, and regular, and covered with small subcircular 

 gquamules along the median transverse or vertical line, these becoming slenderer and more papillifomi 

 toward edges of plate, especially in the fasciolar grooves; at about 1 mm. from upper end of plate an 

 erect, slightly flattened, sharp spinelet attaining a length of 1 to 1.25 mm., and decreasing in length 

 tow anl tip of ray, the series forming a regular longitudinal series at border of abactinal surface; spinelets 

 much reduced in size on first 2 or 3 plates. Inferomarginal plates corresponding exactly to superomar- 

 ginals in number and length, and like them covered with squamiform spinelets, which increase in size 

 toward lower end of plate, but are slender and spinuliform in the fascioles; about I nun. from upper 

 end of each plate a flattened slender tapering spine, attaining a length of 3.5 mm., the series of 

 which extends the length of the ray, except that it is absent from the first 2 or 3 plates. These 

 spines stand out at right angles to the' side of the ray, and are longer than those of the superomarginal 

 series, decreasing, like them, toward the extremity. At a similar distance from the lower end of the 

 plates is another longitudinal series of spinelets. a trifle smaller than the superomarginal series, 1 

 spinelet to a pdate and more or less appressed to the ray, this series extending about 'i the length of 

 ray (to 18th inferomarginal). 



Adambulacral plates with a prominent angular margin to furrow. Armature of the character 

 common to species of Psilaster, rather than that usual to Bathybiaster: (li Furrow series consisting of 

 8 delicate subequal spinelets, a trifle curved, round-tipped or subtruncate, 2 at either end of the 

 series flattened with sides to furrow, the 4 central ones with edges to furrow; lateral-most spinelets 

 often shorter than the others; (2) actinal surface with 2 longitudinal series of flattened, truncate, or 

 round-tipped spinelets. about 5 to each series, outer spinelets slightly wider than inner and all sub- 

 equal to furrow series; both furrow and actinal spinelets incased each in a membraneous sheath, 

 thin on furrow series but pulpy ami thick on actinal spinelets, especially the outer, which appear in con- 

 sequence heavily clavate. It is difficult to make out the arrangement of spinelets unless the specimen 

 is dried. 



Mouth plates long and narrow; armature consisting of a marginal series of 15 short, regular, 

 slightly flattened spinelets, appressed against a superficial scries of 14 heavier, cylindrical, round- 

 tipped or subclavate spinelets, which increase in thickness toward outer end of plate; inner en. 1 of 

 combined pair of plates truncate, 2 spinelets at angle slightly larger and heavier than the others. 

 slightly bent at base, and appressed to innermost of superficial spinelets; all incased in membrane, 

 and the armature as a whole distinctly like Psilaster. 



Actinal intermediate areas small, the plates extending about to 22d inferomarginal or about 5 

 length of ray; plates beset with compact groups of very fleshy, spatulate round-tipped papillae, which 

 become pressed into various shapes by mutual contact; calcareous spinelet within papilla delicate, 



