116 BULLETIN 7t), UNITED STATK3 NATIONAL MnSEUM. 



Remarks. — This species lias the general form of L. lorioli Meissner (Mazatlan), 

 but lias longer arms, which are more attenuate distally. L. ludwigi lacks the con- 

 spicuous sharp spinules which are present in many of the lateral abactinal paxilliB 

 of lorwK, and the latter has no abactinal pedicellariiB, such as are very character- 

 istic of the present species. Another character which separates ludwigi from 

 both lorioli and hcllonsR Liitken is the presence of prominent pedicellariaj on the 

 actinal intermediate plates of interradial region and proximal half of ray. Details 

 of adambulacral armature differ in all three forms. L. ludwigi differs from L. 

 quinaria in having much longer narrower rays, no scattered and abundant abactmal 

 pedicellariiB over the midradial region, and in having three-jawed, not two-jawed, 

 actinal pedicellariiB. The abactinal pedicellarias of quinaria are low, and of the 

 bivalved form of some Goniasteridiv. The adaml)ulacral plates also have two- 

 jawed pedicellariiB in quinaria. 



LDIDIA ASTHENOSOMA Fisher. 



PI. 20, fig. 1; pi. 21, fig. 1 ; pi. 54, fig. 1. 

 Luidia asthenosoma Fisher, Proc. Wash. Acad. Sci., vol. 8, Aug. 14, 1906, p. 124. 



Diagnosis. — Hays five. 11 = 86 mm.; r = 9 mm.; E, = 9.5 r. Breadth of ray 

 at base, 10 to 11 mm. Rays long, narrow, pointed, very gently tapering, with a 

 slightly convex abactinal surface usually sunken along midradial line. General 

 form much flattened; sides of rays rounded; inferomarginal plates narrow, not 

 encroaching much upon actinal area, but forming rather the margin of ray, each 

 with a transverse row of three sharp acicular spmes; ambulacral furrow %vide and 

 shallow; tube feet long, in two series; actinal and margmal spines rather long and 

 bristling, the adambulacral armature, consisting of a transverse row of three promi- 

 nent spinules, forming a series in line vnth. that of mferomarginal plates; actmal 

 intermediate plates usually with a rather short, two-jawed, blunt, papilliform 

 pedicellaria. Paxillse stellate, the superomarginal about twice as large as others. 

 Scattered two or rarely three jawed abactinal pedicellariie are present. Prominent 

 two-jawed pedicellaria on margin of each mouth plate. 



Description. — Abactinal paxillte with a stellate crown; those of supei-o- 

 marginal series larger than rest, and each corresponding to an inferomargmal plate, 

 to upper end of which it is closely juxtaposed. CroA\-n of superomargmal paxilla 

 longitudinally oval (as in sarsi), the others subcircular. Adjacent to superomar- 

 ginal paxilliB are about two regular longitudinal series of lateral abactmal paxillse, 

 about two of which corresjiond to one superomarginal paxilla. Paxilla- dimhiish in 

 size very rapidly toward median line of ray and become less regular in arrangement 

 as they approach it. Superomarginal paxilla has slightly convex tabulum armed 

 with about thirty slender denticulate spine lets, of which about ten are scattered on 

 surface of tabulum and the remainder about the peripherj'-, the whole formmg a 

 divergmg group. The superomarginal and other lateral paxillffi sometimes have a 

 blunt two-jawed pedicellaria similar to but larger than those scattered over the 

 midradial area (see below). The adjacent paxilla- have about twelve peripheral 

 and three to five central spinelets, while those in midradial region have about ten 

 peripheral and three or four central, vcrj- much smaller, spinelets, the whole jiaxilla 



