ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISUEU. 113 



is more active than any form with which I am acquainted. It progresses with ease 

 and comparative rapidity by half walking, half swimming. The large tube feet are 

 waved back and forth and the rays undergo a slight undulatory movement, asthey 

 are ver}- flexible. Wlien kept in stale water or placed in alcohol, the creature will 

 frequently constrict off the arms near the base. These do not fall off at once, but 

 soon break at the line of weakness where one may observe the ])axill.T ]>uiiod apart 

 as if by some violent muscular contraction. 



Remains of ophiurans and several Dentalluin shells were found in about a dozen 

 stomachs examined, both of large and small specimens. 



LDIDIA LUDWIGI Fisher. 

 PI. 20, figs. 2, 3; pi. 21, fig. 2; pi. 54, figs. 2, 2a. 

 Luidia ludwigi Fisher, Proc. Wash. Acad. Sci., vol. 8, Aug. 14, 1906, p. 122. 



Diagnosis. — Rays five. R = 107 mm.; r=13 mm.; R=8.2 r. Breadth of ray 

 at base, 15 mm. Rays slender, very gradually tapering to a pointed extremity; 

 interbrachial arcs acute; general form depressed as in other species of genus, but 

 abactinal surface well arched; sides of ray rounded; abactinal area ^\^th three or 

 four regular series of quadrate paxilla' on each side, the superomarginal with small 

 two and three jawed pechcellaria3 ; inferomarginal plates rather narrow, arched, 

 with one to three, usuaU}' two, lateral spines, and three to six actinal spinules 

 larger than spinelets of general surface, and on upper end a pedicellaria similar to that 

 of adjacent paxilla; actinal intermediate plates of interradial areas and proximal 

 half of ray, each with a rather prominent tlu"ee-jawed pedicellaria; adambulacral 

 plates with a curved furrow spine, tliree actinal spines, and one or two smaller 

 spinules. 



Description. — Abactinal paxillar area is rather crowded and paxilla; of four or 

 five regular lateral series are quadrate, although in the fourth, fd'th, and sixth 

 series (according to size of specimen) many paxillse are subcircular or not obviously 

 quadrate. Superomarginal paxilla? slightly smaller than those of adjacent series; 

 paxilla; thence decreasing in size toward mid-radial area, where they are arranged 

 without regularity and are roundish or irregular in outUne. In some small speci- 

 mens paxillsB are not so obviously quadrate in lateral series, being subcircular in 

 outline, but nevertheless arranged regularl}-. Crown of spinelets not so flat as in 

 foliolata, but rather convex, especialh- in small examples. Superomarginal paxilino 

 with about thirty-five short clavate spinelets in a radiating coordinate group, and 

 most of them also with one or two small two or three jawed valvate pedicellaria, 

 shghtly longer than spinelets; next series with about forty spinelets, those in center 

 of tabuhim stouter than the peripheral, as in superomarginal paxilla'; small mid- 

 radial paxilke with about twenty spinelets, the peripheral series being much slenderer. 

 Paxilla; decrease in size toward center of ilisk. being smaller there than on basal 

 portion of ray. 



Abactinal plates four-lobed as \n foliolata, the lobes being a little shorter and 

 thicker. Superomarginal i)lates with much broader lobes than adjacent abactinal 

 series, being nearer a lozenge-shape with rounded comers. Plates imbricate by 

 57444°— Bull. 76— U 8 



