OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 179 



adoral plates; it is rectangular, and broader than long; the last, 

 which is the smallest, is simply rounded ; it is inserted on the adoral 

 plate. 



The upper arm plates are extremely large and broad, and they 

 cover almost the whole width of the dorsal surface of the arms ; they 

 are almost two and a half times as broad as long, with a slightly 

 concave proximal border, the distal border very broad and convex 

 passing over by very rounded angles into the sides, which are 

 strongly divergent. All these plates are in contact. 



The first under arm plate is considerably reduced, sometimes 

 squeezed in between the adoral plates, which are very close together, 

 sometimes shoved back inwardly from these last; it is triangular, 

 with a distal angle, and a little longer than broad. The following 

 plates are very large and very broad and they cover the greater part 

 of the ventral surface of the arms ; they are quadrangular, almost as 

 broad as long, with an almost straight proximal border, a rounded 

 distal border, and similarly rounded sides which are scarcely de- 

 pressed at the level of the tentacular pores. 



The side arm plates are slightly developed, and only slightly pro- 

 jecting. Each of them carries three small spines, which are rather 

 slender, conical, with the extremity rounded, and of which the length 

 is almost equal to that of the segment. 



The tentacle scales, two in number, are small, rounded, placed side 

 by side, and of similar dimensions. 



Affinities and distinctive features. — Amphioplus luctator differs 

 from all the known species of Amphioplus possessing two tentacle 

 scales and three arm spines in the considerable development of the 

 mouth shields, as well as in the large dimensions of the dorsal and 

 ventral arm plates, while at the same time the tentacle scales remain 

 of relatively small size. In the absence of the dorsal surface of the 

 disk the affinities of this species can not be determined, but I do not 

 see any form with which it may be compared. It obviously differs 

 from the species from stations 5161 and 5371, which I described 

 above under the name of A. lucidus and which possesses several arm 

 spines. 



AMPHIOPLUS RELICTUS (Koehler). 



Plate 70, fig. 9; plate 71, figs. 4-8. 



Amphiura relicta Kcehler ('98), p. 68, pi. 4, figs. 37, 38; ('05), p. 41. 

 Amphioplus relictus H. L. Clark ('15), p. 256. 



Localities. — Albatross station 5206; off western Samar; Badian 

 Island (N.) bearing N. 27° E., 10.66 kilometers (5.75 miles) distant 

 (lat. 11° 31' 40" N., long. 124° 42' 40" E.) ; 58 meters (32 fathoms) ; 

 April 14, 1908 ; gn. M. 



One large specimen (Cat, No. 41257, U.S.N.M.). 



