NEW STARFISHES FROM DEEP WATER OFF CALIFORNIA AND ALASKA. 313 



is usually longest, and commonly theadoral when there are 2; the separate scries well spaced from one 

 another and the spineleta as long as or even longer than the width of the plate; on the actinal surface 

 a series of 4, '■'<, or l' longer and more robust, tapering, pointed spinelets, disposed in an oblique trans- 

 verse series, and decreasing in length as they recede from the furrow, skin-covered, often having lateral 

 expansions, and the bases united by membrane; when there are •"■ or 1 spines, the outer is usually 

 much shorter than the rest. 



Mouth plates fairly large, spade-shaped, and prominent aetinally; median suture wide, roofed 

 with membrane; furrow spinelets 7 or 8, long, skin-covered, united for about J-J their length by a 

 web, increasing very slightly in length toward the innermost, which is rather more robust than the 

 others; near the middle of the suture margin a group of 3 or 4 much slenderer spinelets, which are 

 shorter than those on furrow. 



Actinal rnterradial areas very small, containing small intermediate plates, which bear small paxilhe, 

 and, widely spaced, extend along the ray, here and there, between the inferomarginal and adambula- 

 eral plates nearly to tip of ray. 



Madreporic body small, convex, situated about midway between center of disk and margin. 



Locality; Station 4425, between Santa Barbara and San Nicholas islands, l,084to 1,100 fms., green 

 mud, sand, globigerina. 



Family KORETHRASTERID& Danielssen and Koren, 1884. 



Genus PERIBOLASTER Sladen. 



Peribolaster Sladen, Narr. Challenger Exp., I, 616, lssr> (P. follicxilatus sladen). 



Peribolaster biserialis, new species. 



Rays 5. R=20mm.; r=7.5r. R=2.6r. Breadth of ray at base, 8.5. 



Abactinal surface convex, rather flexible; form stellate; rays rather short and robust, wider than 

 high, tapering, the outer part somewhat slender and often recurved; interbrachial arcs acute, the rays 

 being constricted slightly at the l>ase; edges of ray rounded, due to inflation of abactinal integument; 

 tube feet strictly biserial. 



Abactinal plates stellate, and imbricate by means of rather lung rod-like intermediate ossicles, 

 forming a very open reticulate skeleton with wide interspaces fur the papulae; no serial arrange- 

 ment to the plates, but the papular areas generally quadrate; each plate conspicuously convex 

 and surmounted by a brush-like fasciole of about 5 delicate, glossy, sharp spinules about '■'< mm. long, 

 which are united into a compact group by a membrane, sometimes the spinules radiating a trifle; 

 spinules decreasing in length toward tip of ray, but increasing slightly toward margin; papulae long and 

 conspicuous, 6 or 7 to an area. 



Actinal surface paved with 2 longitudinal rows of band-like plates, which are comparatively wide 

 and short; the adambulaerals bordering the furrow, ami external to them a series of equally regular 

 plates, probably the inferomarginals; adambulaerals much wider than long ami separated by promi- 

 nent sutures; each plate with a transverse series of o prominent spinules, sheathed individually in 

 membrane, which extends beyond the tip in a short sacculus; each spinule surmounting a slight boss 

 on the plate, one situated on the furrow margin, another on the extreme outer margin, and one exactly 

 midway between the two; inner spinule 2 mm. long, and the other 1' successively slightly longer and 

 stouter. 



Inferomarginal I?) plates a trifle longer than adambulaerals and not quite so wide, so that they do 

 not exactly correspond to the latter, even though the sutures are not so prominent; surface of each 

 plate actinal in position and slightly convex, and the outer, lateral end bearing a prominent membrane- 

 invested spinule, 3-3.5 mm. long, which superficially appears to stand in a linear series with the 

 adambulacral armature; inferomarginal spinules, of which about 35 can be counted to the side of each 

 ray, decreasing in size toward extremity, where both marginal and adambulacral plates with their 

 armature are very small; about 10 lateral cruciform plates immediately adjacent to (above) infero- 

 marginals, forming perhaps the superomarginal series. 



Mouth plates very prominent aetinally, the exposed surface rising toward the median suture; the 

 combined pair thus with a very prominent but rounded beak about midway between inner and outer 



