ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 81 



(2 to 3.5 mm. long). When two are present, the adoral is commonly shorter; 

 in some examples these spinules are very short, scarcely more than 1 mm. General 

 surface of the plate bristles with verj- slender spaced capillary spinelets, largest 

 near the spines, these becoming papilliform in some specimens on account of a 

 pulpy membranous sheath. They arc sliorter than adjacent paxillar spinelets. 

 Near each upper coiTier of nearly all the superomarginal plates of type is a small 

 pedicellaria composed of usually four or five (sometimes only two or three) short 

 sharp spinelets, stouter than the rest, arranged in a circle about a common center, 

 or they may be more like the pectinate form characteristic of Cheiraster. The 

 position and number of these varies in different specimens. Sometimes there is 

 but (me, near the upper marginal spine, and in specimens from the northern part 

 of range the pedicellaiise are few, and many of the plates do not have any. In a 

 small specimen (\'ouug) from station 2923 they are very conspicuous. Similar 

 pedicellariEP occur less frequently on the inferomarginals, usually near or on the 

 intermarginal suture. 



Inferomarginal plates corresponding in number to superomarginals, to which 

 they are opposite, forming a steep slightly arched bevel to actinal area. They are 

 also tumid, especially along the transverse axis, the tumidity passing into the 

 corresponding superomarginal without any conspicuous break at the suture between 

 the two. A few of the proximal plates bear a transverse series of three stout, 

 tapering, pointed spines, frequenth- a trifle flattened and bifid hke those of upper 

 series; the rest of the plates, including usually also the first two, bear two such 

 spines, the upper the longer (8 to 9 mm.). Rarely on distal part of ray, where the 

 lower spine is occasionally much reduced in size, there may be either three or four 

 spines, due chiefly to the fact that a spine is split to its base, being in reality two 

 spines with a common articulating boss. These spines are all commonly appressed 

 to ray as in Psilaster. General surface of plates bristles with delicate spaced spine- 

 lets, which increase in size toward lower end of plates and toward summit of 

 tumidity. Pcdicellarire, as described above, are occasionally present. Terminal 

 plate wath apparently two spines. 



Adambulacral plates set obliquely, broader than long at base of ray and longer 

 than broad near tip; furrow margin curved. Armature consisting of (1) a furrow 

 series of five, or less commonly, six (tj-pe) compressed, rather dehcatc, slightly 

 curved, blunt sldn-covered spinelets, often capped with a knobby meml)ran()us 

 tip, arranged palmately, and usually graduated in length from the adoral to the aboral 

 end of series^ or they may be graduated from the midtUe or the second spinelets. 

 There is considerable variation even in the same specimen in the number of furrow 

 spinelets. Some specimens have three or four; and the diameter of spinelets varies 

 according to the thickness of the investing membrane; (2) on actinal surface of 

 plate is an enlarged flattened blunt spine frequently ^\^th a shallow groove running 

 from tip half way to base, this surrountled by a variable number of smaller, tapering, 

 blunt or pointed skin-covered spinelets, arranged frequently in two longitudinal 

 rows, three or four to each, the spine standing in the inner series, or between the 

 two, in wliich case the spinelets appear to form a wide circle around it; outer 

 spinelets usually much flattened at tip and furrowed lengthwise as if incipiently 

 57444'— Bull. 70— 11 6 



