OPHIUBANS OF THE PHILIPPINE AND ADJACENT WATERS. 367 



the five radials touch the dorso central only by a rounded proximal 

 angle; furthermore, they are separated from each other for their 

 entire length by three or four small plates which do not occur in A. 

 The two large interradial plates are smaller, but the third plate, 

 which lies at the periphery of the disk, extends much farther over the 

 dorsal surface than in A. The radial shields are triangular and in 

 contact only for a little more than half of their length. The radial 

 papillae are more developed than in the first specimen, and their 

 spatulate form is still more pronounced. 



The ventral surface of the disk is almost entirely occupied by the 

 mouth shields, which are extremely large. In A, beyond each shield, 

 there is the lower part of the vertical interradial plate which I have 

 noticed above, and which covers only an extremely narrow portion of 

 this surface. The remainder is occupied on either side by a rather 

 large triangular genital plate which disappears toward the middle 

 of the length of the mouth shield and which carries on its free border 

 broad and obtuse papillae which are relatively large and few in num- 

 ber. In B the mouth shields are still larger and the vertical inter- 

 radial plate is not visible on the ventral surface ; these shields cover 

 the whole ventral surface of the disk in the interradial spaces, and 

 the genital plates are themselves very much smaller than in A. . 



As I have just said, the mouth shields are very large, and they 

 occupy the whole ventral surface of the disk except for the more or 

 less reduced portion occupied by the genital plate. They are pentag- 

 onal in form with a very rounded proximal angle bordered by two 

 small excavated sides; this excavation corresponds to the proximal 

 end of the genital slit ; the sides are rounded and they pass over by 

 a very rounded edge to the straight distal border. In A these shields 

 are almost as long as broad; in B they are a little broader than long 

 and the proximal angle is replaced by a rounded border. The adoral 

 plates are narrow and elongated, with a rather sinuous outline ; they 

 are a little broader inwardly than outwardly. The oral plates are 

 large, twice as long as broad, with the borders parallel. The mouth 

 papillae are six or seven in number on either side in A, but their out- 

 lines are not very distinct ; the external papilla is low and broadened ; 

 the following are rounded. In B the papillae are a little larger, and 

 I can only count four of them; the outermost is rounded. The un- 

 paired terminal papilla is conical, and a little larger than those on 

 either side. 



The arms are of medium width, but the segments of which they are 

 composed become very much elongated beyond the disk. 



The first upper arm plate is rather large, trapezoidal, very much 

 broader than long, with the distal border convex. The second is tri- 

 angular, as broad as long, with the angles sharp and the distal border 

 convex. Farther out, the plates are separated by an interval which 



