ASTEROIDEA OF NORTH PACIFIC AND ^VDJACENX WATERS FISHER. 99 



Adambulacral plates about as long; as broaif, not compressed, with a rounded 

 furrow margin and wide sutures between the plates. Furrow spinelets, five or 

 six, usually five, subcylindrical, bluntly i)ointed, the lateral slightly the shortest, 

 the median about as long as plate. On actinal surface of plate are twelve to eighteen 

 spinelets, those adjacent to furrow spinelets largest and forming an irregular series 

 of five or six. The others sometimes suggest two irregular series, but are usually 

 without order. The first plate is shorter than the rest. 



Mouth plate very prominent actinally, the free margin occupying about one- 

 half the length; median sutiu-e, narrow elliptical, the outer end of plates diverging 

 slightly from interradial line. Marginal spinelets eight to ten, slender and pointed, 

 the innermost abruptl}^ larger than remainder. A series of slender blunt spine- 

 lets follows the margin of median suture, and parallel with it an intermediate 

 series, while along the margin adjacent to first adambulacral are several very 

 slender, smaller spinelets, with two or three odd spinelets out of line on surface of 

 plate. 



Actinal interradial areas extensive. The actinal intermediate plates are 

 strongly and narrowly carinated, and a single series extends two-thirds length of 

 ray measured from interradius, a second series about One-third, a third series to 

 the third inferomarginal, and between first inferomarginal and second adambulacral 

 are four intermediate plates in an interradial series. The intermediate plates 

 bear a paxilliform group of rather long slender spaced spinelets, the peripherally 

 placed ones being directed over the deep fasciolar channels between the raised 

 tabula of plates. 



Madreporic body slightly nearer margin than center of disk. It is smaller 

 than in typical Dipsacaster and is entirely obscured by paxillae, one or two of which 

 arise from its surface. The striations are fine and radiating. 



Anatomical notes. — Superambulacral plates present, except on first ambulacral 

 plate, and on the distalmost. Gonads extending far along ray, the genital tubes 

 largest in interradial regions, thence decreasing in size distad. The arrangement 

 appears to be as in typical Dipsacaster except that the genital stolon is nearer 

 marginal plates. Immatiu-e specimens may be found in which the gonads are 

 still confined to the interradial region. Anal aperture present, and easily seen. 

 It connects directly with an unbranched sac-like intestinal ccecum, Ijnng in the 

 left radius of the trivium. Its inner surface is rugose. The opening into the very 

 short intestine is sht-hke, and is situated just below the anal aperture, on a low 

 prominence. A single Polian vesicle in each interradius. Tube feet pointed, 

 without sucking disks, and without deposits in walls. 



Variations. — In some specimens the rays are broader and shorter than in 

 others, and in these the inferomarginals extend laterally beyond the superomar- 

 ginals; while there is also variation in the form of the tip of the ray, this being 

 more rounded in a few e.xamples than in the type. These small di(Terences cause 

 a considerable difference in the general facies of the species. Unfortunately most 

 of the specimens are undoubteiUy young, on account of the condition of the gonads. 

 The variation in the distribution of the genital tubules is due to age, the gonads 

 appearing first in the interradial region and thence progressing along the ray. 

 Fully developed gonads are found in indiviiluals with K = 1.3 nun., but some exam- 

 ples equally large have undeveloped gonads. In such an event one relies upon 



