CLARK: OPHITROIDEA. 447 



ments) l)y a distance greater than their own lenjjth. Intorhrachial 

 areas below covered by ahout half a dozen large plates, with some- 

 times a few much smaller ones among them. Oral shields very 

 similar in appearance to these interbrachial plates, broadly triangular 

 or pentagonal; in one specimen they are as long as wide or longer, 

 while in the other they are distinctly wider than long. Adoral plates 

 very long, straight, and narrow. Oral plates also long and narrow, 

 but shorter and perhaps wider than adorals. Oral papillae about 

 S on each >;ide, very small, subequal. First under arm-plate nearly 

 twice as wide as long, its proximal side very short, like a truncated 

 angle; second plate larger, more swollen, and more nearly rectangular; 

 third plate about like first; succeeding plates smaller and smaller, 

 nearly or quite three times as wade as long; no two of the under 

 arm-plates are in contact an<i the distal ones are very widely separated. 

 Side arm-plates long and relatively large,* meeting broadly both above 

 and below; they are larger distally than proximally, so that the arm 

 seen from either above or below has a wavy outline; each side arm- 

 plate bears 3 short, sharp, subequal spines about half as long as the 

 plate; these spines are borne on the lower half of the distal margin of 

 the plate. Oral tentacle-pores open on face of jaw, entirely outside of 

 mouth-slits ; they have 4 or 5 scales on each side. Tentacle-pores of first 

 arm-segment similar but somewhat smaller, with 3 or 4 tentacle-scales 

 on each side. Tentacle-pore of second arm-segment, much smaller 

 guarded by 2 scales or only 1. Succeeding pores very small and 

 guarded by a single minute scale. Color (dried): — very pale brown. 



Station 4647. Eastern Tropical Pacific, 4° 33' S., 87° 42' 30" W. 

 2005 fms. Bott. temp. 35.4°. Lt. gy. and br. glob. oz. 



Two specimens. 



These specimens are not in good condition, but the specific charac- 

 ters are obvious. The highly arched disk covered by numerous 

 plates, the very slender arms with remarkably reduced upper and 

 under arm-plates, and the reduced condition of the tentacle-pores 

 make an umisual combination, antl gives this Ophiura a very charac- 

 teristic facies. 



Ophiura undulata. 



Ophioglypha undulata Lyman, 1878. Hull. M. C. Z., 5, p. 7.5. 1S82. Chal-^ 



lenger Oph., pi. 5, fig. 10-12. 

 Opfnurn vndulatn Meissner, 1901. Bronn's Thierreichs, 2, abt. 3, j). 92o, 



In the Catalogue of recent ophiurans (Mem. M. C. /., 25) I 

 referred this species to 0. irrorafa as ii synonym. The Challknger 



