Boone, Echinodermata, Cruises of "Eagle" and "Ara," 1921-28 97 



The abactinal surface of this species reminds one of an ox-eyed daisy. 

 The rays are not quite cylindrical, a little depressed dorsally, tapered 

 to a blunt point distally. The disk is not very large, but is usually 

 abruptly elevated at the center. The abactinal skeleton is rather sub- 

 stantial, reticulated with fine meshes. The abactinal spines of the 

 disk are short, thick, with blunt clavate or capitate summit, which 

 under high magnification appears to be composed of rounded granules. 

 These spines are numerous but distinctly separated. On the rays the 

 spines form five definite longitudinal series, a median, a paired lateral 

 and a paired marginal series. In addition there are two series of 

 spines on the sides of the ray, which are slightly smaller than those 



A 



B 



Text fig. 3. — Eeliaster multiradiatus (J. E. Gray). A. Section of abactinal sur- 

 face of arm. B. Section across actinal surface of arm, both much enlarged. 



of the actinal series. On the abactinal surface the largest spines are 

 usually on the disk and the median series of the rays. The present 

 specimen also has several "twin" or double spines, with one base 

 splitting into two normal size spines distally. The actinal surface of 

 the disk has the interbrachial areas reduced to a minimum, the sur- 

 face being almost completely occupied by the ambulacra, adambu- 

 lacral spines, pedicellariae and papulae. The actinal spines are in 

 two series, an upper row in which the spines are shorter than the 

 adambulacral spines, and the lower series which is longer than these 

 latter. The adambulacral spines are close-set; usually each plate has 

 a long, clavate outer spine, and closely appressed to this on the inner 

 side is a second spine, which in some instances is a duplicate of the 

 outer adambulacral spine, making a double series, but in other 



