SHALLOW- WATER STARFISHES 311 



A pair of muscle-bands extends along the medio-dorsal region for 

 a part of the length of the rays. Dorsal pore usually distinct. Ambu- 

 lacral feet have suckers. 



Ludwig (1910) has proposed a special order (Myonota) for this 

 family, on account of the presence of dorsal radial muscle-bands. 



It seems to me desirable to retain two subfamilies in this group, 

 though recently discovered genera render them less distinct than 

 formerly. 



Subfamily BENTHOPECTININJE Verrill, 1894, p. 245. 

 Benthopectinida (family) VERRILL, 1899, p. 217. Ludwig, 1910, p. 435. 



This group will include those genera in which an odd interradial 

 marginal plate normally exists in part or all the interradial areas 

 in both rows. The papulae are not concentrated in specialized 

 papularia, though they may be confined, in some genera, to the basal 

 part of the rays. Abactinal plates are flat or low tabulate, usually 

 lobed, sometimes stellate, bearing one or more large, sharp spines 

 and usually many smaller accessory spines. 



This is a strictly deep-sea group. Several species have been 

 described by Dr. Fisher from the North Pacific. It includes the 

 genera Benthopecten Verrill; Myonotus Fisher; and Nearchaster 

 Fisher. 



Subfamily PONTASTERIN& Verrill, 1899. 



Cheirasteridce (family) LUDWIG, 1910, p. 435. 

 Benthopectinidee (pars) FISHER, op. cit, 1910, p. 120. 



Odd marginal interradial plates are not normally present. Papulae 

 are confined to the basal parts of the rays, and are often concentrated 

 in specialized papularia. 



This group is almost entirely confined to the deep sea. Several 

 species are known from the North Pacific in deep water. Only one 

 comes within my bounds. 



Genus Luidiaster Studer. 



A canthar chaster VERRILL, Proc. U. S. Nat. Mus., xvii, p. 268, 1894. 

 Luidiaster STUDER, 1883, p. 131. Ludwig, 1910, p. 451. Fisher, op. cit, 19116, 

 p. 127. 



Rays usually five, angular, tapered. Disk small. Interradial 

 actinal plates few, confined to the disk, spinous. Marginal plates 

 of moderate size, more or less alternate, spiniferous; those of the 

 upper series smaller than those of the lower, rounded, with a central 



