OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 69 



much broader than long, with the proximal border very much shorter 

 than the distal. The following plates are very large, triangular, a 

 little broader than long, with an obtuse proximal angle, convex sides, 

 and a very large distal border similarly convex. This distal border 

 at first bears three or four spines identical with those on the dorsal 

 surface of the disk, but the number of these spines rapidly diminishes, 

 and they usually disappear for good on about the tenth segment. At 

 this level the plates, which, up to now, were in contact, become sepa- 

 rated by a narrow space. 



The first under arm plate is rather small, broader than long, pen- 

 tagonal, with a very obtuse proximal angle and a small distal border. 

 The second, which is at least four times as broad as long, is already 

 separated from the first ; it shows a very obtuse proximal angle bor- 

 dered by two gently concave sides, sharp lateral angles, and a very 

 broad distal side slightly notched in the middle. The following 

 plates, always rather broadly separated from each other, at first re- 

 tain a form similar to that of the preceding, but the proximal angle 

 disappears almost completely ; the plates then become quadrangular, 

 with an almost straight proximal border, a slightly concave distal 

 border, and two very rounded sides which, passing over very rounded 

 angles, unite to form the two long borders. Toward the seventh or 

 eighth the plates become smaller, and the proximal side diminishes 

 rapidly, being subsequently replaced by an obtuse angle; from then 

 on the plates assume a pentagonal form with an obtuse proximal 

 angle bounded by two straight sides, two straight lateral borders, 

 and a very broad distal border, while at the same time the interval 

 which separates them becomes somewhat greater. Little by little the 

 width of the plates diminishes and correlatively their length in- 

 creases, and they then become as long as broad, the interval which 

 separates them increasing still more. 



The side arm plates, which project only slightly, carry at the base 

 of the arms seven slender, pointed, and finely echinulated spines; 

 their length increases from the first ventral, which is shorter than the 

 segment, to the antepenultimate dorsal, which equals two segments 

 and a half ; the last is a little shorter. These spines are only slightly 

 divergent, remaining in general close to the plates which bear them, 

 without, however, being appressed to them as in the genus Opkio- 

 limna. The single large tentacle scale is broadened on the pores of 

 the first pair, where it is almost as broad as long. It becomes a little, 

 narrower on the following segments, and, beyond the disk, it becomes 

 progressively more and more narrow, and finally three times as 

 long as broad with the tip rather pointed. 



The specimens in alcohol are slightly pink. The dorsal surface of 

 the disk shows numerous small, rounded brown spots near together. 



