ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 193 



series of plates together form a rounded margin to ray. Plates covered with tliick- 

 ened papilliform granules or stumpy spinelets, like those on adjacent paxilia?, these 

 increasing in length towanl lower edge and passing without lireak into spinelets of 

 inferomarginals. On proximal third of ray two or three spinelets near lower end of 

 plate are enlarged into more robust clavate spinules, which in interbrachial arc form 

 a transverse row, or a group with several spinelets of intermediate size. All are 

 incased in membranous sheaths. 



Inferomarginals oj^posito superomarginals and encroach much more on actinal 

 area than do superomarginals on abactinal. They are likewise tumid and arc cov- 

 ered with rather slender jjapilliform spinelets (thickly cased with membrane), 

 which may become subsquamiform. Enlargeil flattened lanceolate si)inules form an 

 irregular transverse series of four or five, or there may be an oblique series of two or 

 three near inner end of jilatc, and a longitudinal series or group of several onlv 

 slightly enlarged spinelets at upper end of i)late. The spinelets are jiacked together 

 and rather difficult to diagnose, inasmuch as they vary in length and intergrade 

 with the enlarged spinules. Terminal plate small, apparently granular, and ovoid 

 in shape. 



Adambulacral plates with an acute furrow angle projecting conspicuously 

 between adjacent tube feet. These projections are rather widely spaced owing to 

 the length of the plates. Armature spiniform, not granuliform. It is difiicult to 

 diagnose exactly the armature owing to slight variations. On the very angular 

 margin are five to eight fairly slender tapering spinelets, with membranous covering, 

 which cause them to appear flattened and blunt. The median, on the apex of angle, 

 is usually slightly longer than rest. On actinal surface are two to five delicate 

 spinelets and usually one or two enlarged sharp spinules sheathed in membrane. Of 

 the latter there is usualh' but one at base of ray, and two distally, where they are 

 more prominent. A peculiarity of the plates is the fact that at base of ray they are 

 so spaced that an intermediate plate may border the furrow for a shoi-t distance, 

 and two or three actinal intermediate spinelets may stand in between two consecu- 

 tive furrow series. Very soon, however, the plates come close enough together to 

 have transverse sutures. 



Actinal interradial areas largo, paved with rather small superficially oblong, 

 squarish, or even nearly round plates arranged in series running from ailambulacral 

 to mai^in. Internally the jjlateg imbricate, and are broadly irregular oval in form. 

 On the ray the plates also form longitudinal series, one extending about O.S length 

 of ray, a second over O.C), a third about 0..5. On the basal half the longitudinal series 

 are not distinct except the two or three adjacent to furrow. The plates are armed 

 with slender spacetl spinelets directed toward margin. These are slightly clavate 

 or are terete, vary in length, and are normally sheathed in membrane, which may 

 become thickened at end, obscuring sharp or blunt tips. One or two enlarged, more 

 robust spinules stand on each plate. Very narrow, shallow channels separate the 

 consecutive interradial or transverse series of plates. 



On the basal third of ray, on the transverse suture separating consecutive 

 actinal intermediate plates of the series adjacent to adambulacrals is a valvate pedi- 

 r>7444°— Bull.-fi— 11 13 



