200 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



central spines have the tip obtuse and slightly broadened; the ex- 

 tremity is armed with little asperities as in the type, and one of them 

 is a little more developed than the others, but without forming a 

 true hook (pi. 96, fig. 12). 



In spite of the slightly different form of the outermost mouth 

 papilla, I do not believe that there is any necessity for separating 

 this specimen from Ophiocentrus asper. 



OPHIOCENTRUS VEXATOR, new species. 



Plate 62, figs. 1-5; plate 96, fig. 11. 



Locality. Albatross station 5181; off eastern Panay; Antonia 

 Island (S.) bearing S. 63 W., 12.25 kilometers (6.6 miles) distant 

 (lat. 11 36' 40" K, long. 123 26' 35" E.) ; 47 meters (26 fathoms) ; 

 March 27, 1908; M., fne. S. 



Two specimens (Cat. Nos. E. 10, E. 11, U.S.N.M.). 



Description. The larger specimen, which I have taken as the type, 

 is almost complete. The disk is slightly deformed and measures 12 

 mm. by 9 mm. in diameter ; the arms, almost all complete, are about 

 60 mm. to TO mm. long. In the other specimen the incomplete disk 

 is 10 mm. in diameter, and a single arm is preserved. 



The dorsal surface of the disk is covered with extremely small 

 imbricated plates, with indistinct outlines, some of which bear a 

 rather thick, but not very long, conical spine with the point blunted. 

 These spines become more closely crowded toward the periphery of 

 the disk. The radial shields are three times as long as broad, with a 

 rounded proximal angle ; their form is that of a slightly curved tri- 

 angle. The two shields of each pair are sometimes very close to- 

 gether outwardly without, however, being in contact, and they di- 

 verge in such a way as to leave between them a rather broad space: 

 the separation of the shields varies in the different pairs. 



The ventral surface of the disk is covered with small rounded, 

 imbricated, equal plates, which are very finely granulose and pro- 

 vided with more pointed spines than those on the plates of the dorsal 

 surface ; these spines are very closely crowded toward the periphery 

 of the disk, but they disappear rapidly before reaching the mouth 

 shields, leaving a more or less extensive portion of the ventral surface 

 naked. The genital slits are very narrow and elongated. 



The mouth shields are longer than broad ; they have a form recall- 

 ing that of a very short rocket, or, in other words, they show a trans- 

 versely broadened and oval principal portion with a broad and 

 slightly convex proximal border and the angles and sides very 

 strongly rounded, plus a lobe which projects into the interradial space 

 and which is almost as long as broad with the distal border rounded. 



