SHALLOW-WATER STARFISHES 189 



The arrangement of the adambulacral spines is peculiar, for while 

 the plates bear alternately two and three spines, the inner spine of 

 the alternate plates is attached deep within the groove on a special 

 lobe of the inner edge of the plate, while the two outer ones stand 

 on the actinal end, nearly in line with the spines of the adjacent 

 actinal plates ; thus they seem to form four or five rows. Jaw-plates 

 bear two pairs of apical oral spines, one above the other. 



The interradial areas, near the jaws, are without spines and in the 

 dry specimens they are sunken in the form of pits. The position of 

 the genital pores was not determined for lack of alcoholic specimens. 



ALLASTERIAS RATHBUNI Verrill. 



Plate LXXVIII, figure 2 (details), var. nortonensis. 



Allasterios rathbuni VERRILL (pars), Amer. Journ. Sci., xxvra, p. 65, 1909, 



figs. 5, 6, 7 (as varieties). 

 Asterias rubens ? MURDOCH, Rep. Int. Polar Expedition to Point Barrow, p. 



159, 1885 (MOM Linne). 



Rays five, broad at base and rapidly tapering to acute tips. Radii, 

 25 mm. and 100 mm. ; ratio, 1 : 4. Small major pedicellariae are 

 abundant all over the dorsal and lateral surfaces. 



Dorsal skeleton rather feeble, composed of a great number of 

 small ossicles, arranged in an openly reticulated manner, so that the 

 texture is rather soft and flaccid, in alcohol. The dorsal papular 

 areas are numerous and contain many small papulae. Disk rather 

 broad, but probably abnormally so in the dried specimens, owing to 

 the flattening when soft. 



The whole dorsal surface is conspicuously areolate or reticulate, 

 the areolations mostly 1.5 mm. to 2 mm. broad. The dorsal spines 

 are very small and numerous, sometimes" almost like round or capi- 

 tate granules, being scarcely higher than thick, but in other examples 

 clavate or partly acute ; they are scattered or arranged in single rows 

 on all the ossicles, so as to form a border around the papular areas ; 

 toward the sides of the rays they are distinctly longer and mostly 

 clavate or subacute. 



The superomarginal spines form a wide band of small, crowded 

 spines, five to ten or more on a plate. They are mostly larger and 

 longer than the dorsals, and two or three times as long as thick, 

 mostly cylindrical or clavate, sometimes gouge-shaped. Below this 

 band there is a broad intermarginal channel with large papular areas 

 and numerous rather large, pointed major pedicellariae. This chan- 

 nel rapidly widens at the bases of the rays. 



