50 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



less diversity in color, for although the rays are sometimes transversely banded, 



kubiniji is always darker than multiradiatus, the yellow being much deeper, often 



becoming quite brown. Comparatively little variation in the amount of ray that 

 is free is shown, the very great majority of specimens having half or a trifle less. 



Material examined: — 



42 specimens. Acapulco, Mexico. M. C. Z. collection. 



20 " Mazatlan, " " «' 



5 " Loc? 



15 " Cape St. Lucas, L. C. U. S. N. M. " 



16 " Pichilingue Bay, L. C. 



5 " " Lower California." " 



4 " La Paz, L. C 



3 " Guaymas, Mexico. " " 



2 " San Luis Gonzales Bay. " '* 



1 specimen " Gulf of California." 



1 " San Juan, L. C. 



1 " " Guanajuato, Mexico." 



1 " " Colorado Desert." 



116 specimens. 13 localities. 

 Heliaster microbrachius Xantus. 



Plate 1 ; Plate 7, Fig. 1 1. 



Heliaster microbrachia. Xantus, 1860. 

 Asterias helianthus Stimpson, 1857.? 

 Asterias microbrachia Liitken, 1871. 

 Heliaster microbrachius Leipoldt, 1895. 



Description. — Kays 27-44, averaging (37 individuals) 34.7; about 25 (20-30) per 

 cent of ray free. R = 60-125 mm. ; r = 45-95 mm. Breadth of ray at base 8-15 

 mm. R = 7-8 br. Rays more or less flattened abactinally, tapering rather sharply 

 to a blunt point. Disc very large, somewhat elevated in well-preserved specimens, 

 but not abruptly so. Abactinal skeleton stout, closely reticulated, with small 

 meshes. Abactinal spines very numerous, 35-50 or even more per sq. cm., small, 

 usually low, more or less cylindrical and without definite arrangement. In some 

 large specimens the spines show a slight tendency to be capitate, and in many 

 cases they are very evidently compressed. In some individuals the spines on the 

 rays form five fairly distinct series, and these can be followed inward for a variable 

 distance onto the disc. At the edge of the disc the marginal series of adjoining rajs 

 are sometimes very clearly separated by a bare space about 2 mm. broad, but in full- 

 grown specimens this arrangement is not usually distinct. — Sides of ray with two 

 series of compressed spines. Actinal surface very much as in helianthus, but pedi- 

 cellariae are as a rule less frequent, and the reduction of the adambulacral armature 

 reaches its extreme, for in large specimens only every other adambulacral plate 

 bears a spine until the distal half or even third of the furrow is reached, and even 

 at the extreme tip of the ray it is rare to find a plate with two spines. — Pedicels 

 rather numerous, distinctly quadriserial at the middle of the ray. — Madreporite 

 rather small, often concave, and usually fragmented. — Color of abactinal surface 

 purplish- or grayish-black ; spines deep yellow or whitish ; actinal surface whitish, 



