ASTEBOIDEA OF NOKTH PACIFIC AND ADJACENT WATERS — FISHEK. 35 



cceca large, extending nearly to end of ray, and with spacious cavity. Gonads 

 intcrradial, one on either side of the membranous interradial septum. Ampullae 

 single; tube feet large, conical, pointed; no deposits in walls; one Polian vesicle 

 to each interradius. 



Superambulacral plates present; absent from first and sometimes second 

 ambulacra! ossicle and also from last six or eight at end of ray. These plates are 

 not very conspicuous, being dorsovcntrally flattened and overlaid b}^ membrane. 

 Although Ludwig " states that they are absent from his specimens (Panama region), 

 I think he must have overlooked them. They are very easily seen if a portion of 

 the ray is treated with caustic potash solution. They are present in a specimen 

 examined, from station 3307, from the great depth of 1,033 fathoms. I also dis- 

 sected a specimen from station 2452, off Newfoundland, 89 fathoms, and the 

 superambulacral ossicles are present. 



In the center of the conical abactinal prolongation one can easily distinguish 

 in many specimens a small "pore" evidently connecting \vith the body cavity. 

 This is also present in many Eremicaster tenehrarius, and is what Sladen took to be 

 an anus in PorceUanaster. I think it must be an artificial opening caused by a 

 stretching of the abactinal membrane at the summit of the cone, and possibly 

 subsequent wearing, as the rudimentary paxillse are usually more or less M'orn 

 down here. 



The walls of the stomach contain numerous small straight or irregular rods 

 antl grains from 0.01 to 0.175 mm. in length. They are sometunes provided with 

 irregularities on sides or are irregularly triradiate. They are found also in the 

 walls of the hepatic coeca, but are not so numerous. On the lips of the peristome 

 they are transformed into broader irregular flattened rods with a few perforations, 

 but in the peristome itself are comparatively few scattered rods like those of stomach 

 walls, and only near the lip are they perforated. In the wall of stomach near 

 mouth the rods are usually simple and very regular, and tend to arrange themselves 

 in close meridional series. 



Japanese specimens. — I have eight specimens from station 4S18, Sea of Japan, 

 225 fathoms. One of the largest of these is figured. All have very small low 

 paxillse with comparatively few spinelets. The superomarginals are also slightly 

 narrower than in shallow-water Alaskan examples, but about as in specimens from 

 1,033 fathoms, Bering Sea. (The latter have large paxilltp, with usually high 

 pedicels, which lack entirely the central spinelets.) The Japanese specimens have 

 four, but occasionally also three and five furrow spines. 



Another specimen from station 5039, south coast of Ilokushu, 326 fathoms, 

 is very different, having narrower and longer rays (K = 3 r), large paxilhv, with 

 comparatively long pedicels, the summit of which lacks central spinelets, and small 

 actinolateral spinules. There are four furrow spines, as in the Japan Sea examples. 

 This is also figured. 



Superambulacral plates are present. 



Distribution. — Bering Sea, along the north coast of America to Melville Island; 

 through Barrow Strait to Greenland; south along the east coast of North America 

 to Cape Cod; west ami north of Spitzbergen to latitude 80° 3' N.; south to Faroe 



oMem. MuB. Comp. Zool., vol. 32, 1905, p. 105. 



