ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 377 



The paxillse of the median radiul rc{,'i()ii arc very small, with short spincicts 

 and pedicels beyond the ])r<)xinial third of li, hut on either side they rapidly increase 

 in length, the Interaliuost or marginni being the largest. This striking discrep- 

 ancy in size results in the nidamental cavity being almost entirely interradial, as 

 the supradorsal membrane rests u\nm the ambulacral ridge beyond the proximal 

 third of K. The radial paxilla- at about the middle of K measure 2 mm. or less in 

 height (the j)e(liccl being too short to measure). A corresponding inferomarginal 

 paxilla measures: pedicel, 4 mm., + s[)ines, 6 mm. (station 2919). On the outer 

 third of the radial line the scattered paxilUe are rudimentary and simply anchor 

 the supradorsal membrane to the very thin nbactinal integument. Small paxilla; 

 have three very slender spinelets; the larger adradial, three; and the marginal, 

 three to five spines, all verj- slender. Osculum large, the valves with about 

 eighteen spines on the side toward aperture and about five short ones back of 

 these. The lateral spinelets of the comb rn[)idly become smaller. (PI. 115, figs. 

 la, 16.) 



The abactinal skeleton is exceedingly weak, the processes forming the base 

 of the paxilla" being unusualh' k>ng and slender. The inferomarginal plates have 

 four, the superomarginal three proximally, two distally, and the abactinal one to 

 three. The interspaces are unusually large, especially along the medioradial area. 

 The two adoral processes of the inferomarginal ])axilla' are longer than the two 

 aboral, and the inferior branch of the superomarginal plates is stouter an<l a trifle 

 longer than the one or two processes directed niesially. The tnie abactinal plates 

 have almost thread-Uke processes and are in three irregular series, a radial and on 

 either side an adradial, the latter with usually three processes proximally and two 

 on outer part of ray. Pro.\inially the processes of the plates touch, but distally 

 the radial series of rudimentary ])a.\illtr has often only a single long, slender process, 

 which may not be in connection with any other plate. The inconstant number 

 of lobes results in an irregular mesh, the integument of which on the proximal 

 part of the ray contains irregular, elongated scatteretl thin |)lates, consisting of a 

 single layer of calcareous reticulum. The membrane between the primary radial 

 or oscular valve plates ami anal aperture contains numerous large, tliin subcircular 

 or elongated plates. (PI. 115, figs. 1, If, 1*/, Ir.) 



Papida' large on the proximal part of the ray, small and coniineil to the lateral 

 parts of ray beyond the middle of R. The distal fourth of K is without papula". 

 The papuhe are saccular, anil the surface is subdivided into many small outpock- 

 etings, giving the appearance of a miniature caulillower. The papula* staml alone 

 (not attached to paxilla*), anil the i)roximal are often filled with the hepatic ccpca. 



Mailreporic body very large and jirominent, being about as high as wide, 

 subglobose, and marked with fine branching centrifugal stria*. It is situated not 

 interradially, but next to a primary radial or oscular paxilla. The actual disk is 

 so small the plate has become pushed to one side. 



Actual disk very small; K = S5 mm., actual r= 10 to 14 mm.; diameter of ray at 

 ba.se about 15 mm.; diameter of mailreporic body 8 to 10 mm. Thus it is evident 

 the actinolateral membrane is very wide and the interradial cavities spacious. (See 

 dimensions above.) 



