the Echihodermata of the Arctic Expedition. 455 



pies occuiTed in Capt. Feilden's dredging in lat. 65° N., 

 26 miles from the Greenland coast, at a depth of 30 fathoms. 



Aster acanthion palceocrystallus^ n. sp. 



In general appearance this starfish bears a strong resem- 

 blance to a Cribrella, the rays, five in number, being round 

 and tumid ; they are long and taper considerably towards the 

 point. The disk is small, its diameter being proportional to 

 that of the rays as 1 : 5*5. Skin semitransparent, not corru- 

 gated, and investing thickly every appendage of the body. 

 Ambulacral pores well-spaced, forming two simple rows of 

 sucker-feet, as in Stichaster. Each interambulacral plate 

 bears two very slender spines, which form two regular rows, 

 one radiating towards the furrow, the other to the margin. 

 The spnies upon the sides of the arms are much shorter than 

 the ambulacral spines, and comparatively more robust, and 

 are the same in size and character as the spinelets of the 

 dorsal surface. The ossicles of the abactinal network are 

 arranged more quadrilaterally than is usual in Asteracanthion] 

 a regular median line passes down each ray, the others run- 

 ning parallel and transverse to this with more or less regu- 

 larity . Only a single spinelet is given off at each decussation, 

 with an additional one, frequently, on the imbricating ossicle; 

 the spinelets are consequently widely spaced and assume 

 (although somewhat irregularly) a fairly rectilineal arrange- 

 ment. The spinelets are of the same shape and structure as 

 in Stichaster ; they are deeply grooved, and have 3-5 denti- 

 cles proceeding from their truncate and slightly radiate apex. 

 The ambulacral spines have the shafts also denticulate. The 

 pedicellarife (" croises," Perrier) are more numerous upon the 

 dorsal surface than the spinelets, amongst which they are 

 placed separately and at intervals apart. These pedicellariaa 

 are large and closely resemble those of Stichaster^ the fore 

 part of the "jaw" being very gibbous and truncate. The 

 pedlcellariai together with the dorsal spinelets, which are but 

 little longer, are covered with a thick investing membrane, 

 which, in spirit preparations, gives quite a papillate appear- 

 ance to the starfish. 



Upon the disk the spines are somewhat more crowded tlian 

 upon the rays ; and the " eye "-spines at the tip of the rays 

 form a robust terminal fringe. The madreporiform plate is 

 obscure ; and of the large simple pediccllariai there are but 

 very few. 



Although this species resembles Stichaster in so many 

 respects, the arrangement of tlie dorsal ossicles is hardly such 

 as would include it within tliat genus. A. j^a^o^ocrystallus 



