46 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



little species is more nearly related to helianthus than to the species with rela- 

 tively few rays. 



Material examined: — 27 specimens, Juan Fernandez, M. C. Z. collection. 



Heliaster multiradiatus (Gray). 



Plate 4, Fig. 1. 



Asterias midtiradiata Gray, 1840. 



Heliaster multiradiatus Dujardin and Hupe, 1862. 



Heliaster multiradiata Verrill, 1867. 



Description. — Rays 21-27, averaging (10 individuals) 23.8 ; about 60 (50-70) per 

 cent of ray free. R = 60-100 mm. ; r = 25-47 mm. Breadth of ray at base, 6-12 

 mm. R = 8-10 br. Rays more or less distinctly cylindrical, sometimes slightly 

 flattened and rather angular abactinally, especially near middle. Disc moderate, 

 more or less distinctly and abruptly elevated at centre. Abactinal skeleton mod- 

 erately stout, reticulate, with rather small meshes. Abactinal spines not very 

 numerous, about 10-16 per sq. cm., moderately stout, high, especially on disc, and 

 more or less cylindrical, sometimes thickened, clavate or capitate at the summit. 

 No evident arrangement on disc, but on rays a median series, with a lateral and 

 marginal series on each side (five series in all), can generally be clearly distin- 

 guished, though sometimes there appear to be six series, or again only four. The 

 largest spines are on disc and at base of ray, the smallest near tip of ray ; the 

 median series is usually somewhat larger than the others. — Sides of ray with two 

 series of compressed spines, which are usually shorter than the adjoining actinal 

 series. Actinal surface much as in helianthus and the other species, but the adam- 

 bulacral armature is somewhat different, for the large spines do not alternate with 

 small ones, but are practically uniform in size, and on many of the plates a second 

 smaller spine stands on the inner edge, thus making the armature of the furrow 

 double. In some specimens nearly the whole series is double, while in others two 

 spines are to be found only on scattered plates. Occasionally three spines occur 

 on a single plate. The larger spines are about three millimeters long, quite slender, 

 and nearly cylindrical. Outside of the adambulacral series are two rows of actinal 

 spines, the lower of which consists of spines longer and heavier than the adambu- 

 lacral, while the upper are somewhat smaller. These two series, but especially the 

 lower, extend inward well onto the interbrachial area. Towards the tip of the ray 

 all of the large spines become greatly reduced, so that the 15-17 series which sur- 

 round the tip are of nearly uniform size, though the adambulacral and adjoining 

 series are still distinguishably larger. Buccal depression as in helianthus. — Pedi- 

 cels not very numerous or crowded, so that they are not truly quadriserial at any 

 point. Pedicellariae mostly small, numerous, especially on abactinal side of rays 

 near tip ; sometimes very large f orficate pedicellariae occur on the actinal surface. 

 Madreporite rather small, usually simple and convex, very rarely showing any 

 trace of fragmentation. — Color of abactinal surface, light gray, yellowish, or 

 whitish, irregularly blotched with dark gray or blackish ; on the rays the dark 

 blotches appear as irregular cross-bands ; spines whitish, yellowish, or brownish ; 

 actinal surface mostly light yellow or whitish, but interbrachial areas and outer 

 side of large adambulacral spines on proximal half of rays tend to become black- 

 ish, and in most specimens there is a striking contrast between the inner and the 



