ASTEKOIDEA OF NOKTU PACll'IC AND ADJACENT WATERS FISHER. 351 



^Vrmature of mouth plate's consisting of a marjjinul scries of fmir spines ftnd 

 spinelets, the inner long and slenth-r, tlie next nearly as lonjj, and tlie outer two 

 much shorter; inner three united by menihranc, and usually also the whole four, 

 but the outermost, wiiich is siiortcst, sometimes stands alone; on tiie actinal surface 

 commonly one long, slender spine about tiie size of the inner marginal, with which 

 it stands in a linear series, directed over the outer end of the plate : tiiis spine entirely 

 free from tiie others. Sometimes there are only three marginal spines. The outer 

 enil of the combined mouth plates forms a peak in tlie center, the median suture 

 sloping upward at a rather steep incline. 



Actinolatoral membrane narrow, only a trifle wider than furrow at base; spines 

 short, the ninth or tenth the longest; for a considerah)le distance along ray they 

 shorten only slightly or not at all. Membrane rather thin, forming a lateral fringe 

 with an undulating edge. In some states of contraction this edge is free from the 

 supradorsal membrane for one-third or one-fourth of its width. 



Color in life, "dragon's blood" red. 



Anatomical notes. — Hepatic coeca relatively enormous, extending to tip of ray, 

 the interior a very spacious cavity from which food is probably absorbed. Between 

 the large dorsal stomach and the anus is a spacious saclike intestine with WTinkled 

 walls which probably function as tlie intestinal coeca of other forms. There is a 

 powerful sphincter between the dorsal stomach and intestine. Dorsal stomach 

 spacious with large dorso-ventral slits opening into each of the ten hepatic ccpca, 

 which are connected with the first ambulacral ossicles by strong bands of muscle, 

 probably to draw the coeca toward the mouth when the stomach is thrown out. 

 The lirst ambulacral ossicle is very large and arched. To it are attached along the 

 inner face numerous muscles apparently protractors and retractors of the ventral 

 or eversible stomach. The first tube foot lias a single large ampulla, the succeeiling 

 tube-feet have two. The upper ends of the ambulacral ossicles are strongly imbri- 

 cated and are very flaring. Tube feet with large suckuig disks, in two zigzag or 

 virtually four series; alternate pores are placed nearer the adambulacral plates so 

 that the feet are really four ranked. No Polian vesicles; madreporic canal rather 

 long and sinuous. Interradial septa of tough membrane, attached to either sitle of 

 which is the gonad, forming a large much branched tuft. Gonads packed with 

 sperm. 



Abactinal plates with four long slender arms widening at the end. These 

 overlap the lobes of adjacent plates and form square papular areas. 



Tijpe.— Cat. No. 22343, U. S. N. M. 



Type-locality. — Albatrof!s station 4354, o(T San Diego, California. 046 to 650 

 fathoms, green mud. 



Distribution. — From northern Ix)wer Califumia to Washington, in 266 to 9S4 

 fathoms, on mud or sand. 



