SHALIX)W-WATER STARFISHES I9I 



The arrangement of the adambulacral spines is so peculiar that it 

 should, even on that account alone, form the type of a genus. But it 

 is also peculiar in the structure of the dorsal skeleton, the character 

 of the marginal spines, etc. 



The only other species known to me, besides the following four, 

 described as having a similar arrangement of a row of spines within 

 the groove, is A. versicolor (Sladen), from oflF Kobe, Japan, In 

 that species the alternate plates bear only one spine, and the dorsal 

 and lateral spines are larger, much less numerous, and differently 

 arranged. It evidently belongs to the same genus. 



Besides A. versicolor, there is another species, A. amurensis Lut- 

 ken, as Asterias, from further north, on the Asiatic coast, and also 

 recorded from Yokohama by Sladen, that must bear considerable 

 resemblance to our species, though the dorsal and upper marginal 

 spines are fewer and longer. Liitken, however, does not mention any 

 such peailiar arrangement of the adambulacral spines as is found in 

 this group. I have had no opportunity to study his species. 



A small Korean starfish, described by Sladen (1878, p. 432), under 

 the name of Asterias rubens, var. migratum, probably belongs to this 

 genus, and should be called Allasterias migrata, but its immaturity 

 (greater radius of the larger specimen, 16 mm.) renders it impossible 

 to determine whether it be distinct from the other known species, 

 until a series can be studied. 



ALLASTERIAS RATHBUNI NORTONENSIS Verrill. 

 Plate Lxxviii, figure 2 (details of type) ; text-figures Nos. 8, 9. 

 Allasterias rathbuni, var. nortonensis Verrill, op. cit., 1909, p. 66, fig. 7. 



Rays five, broad at base, depressed, acute. Radii of the type are 

 22 mm. and 82 mm. ; ratio, i : 3.8. 



The dorsal spines are numerous, pretty evenly spaced and scat- 

 tered over the rays and disk on the openly reticulated, slender 

 ossicles. They are partly blunt, cylindric, and partly clavate, but not 

 strongly so, rather longer than in the typical form. Papular areas 

 are large, with many small papulae and scattered small dermal pedi- 

 cellariae. Madreporic plate large and strongly convex. The dorsal 

 spines bear but few minor pedicellariae. Some larger acute major 

 pedicellarise occur among the spines. 



The adambulacral spines stand mostly two and three to a plate in 

 alternation. The inner or furrow spines are elongated, tapered, sub- 

 acute and often bear a cluster of small major pedicellariae. The outer 



