OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 99 



easily recognized. All the plates of the dorsal surface of the disk 

 are not provided with globules, these occurring especially on either 

 side of the groove which divides the dorsal surface in the damaged 

 specimen, as well as at the periphery of the disk and between the 

 radial shields; they are also found here and there on certain plates 

 (fig. 4). In the specimen from station 5348 the granules, which are 

 few in number, occur only on the periphery of the disk (fig. 9). 

 The medium-sized radial shields are triangular, almost as broad 

 as long, with the angles much rounded ; the two shields of each pair 

 are in contact throughout almost their entire length, and their distal 

 extremities alone are separated. In the specimen from station 5173 

 the two shields are separated from each other over a somewhat 

 greater distance. 



The ventral surface of the disk in the interradial areas is covered 

 with subequal. imbricated plates, very much smaller than those of 

 the dorsal surface, and entirely without granules. The genital slits 

 are narrow. 



The medium-sized mouth shields are triangular, a little broader 

 than long, with a rather open proximal angle bounded by two 

 straight sides; the lateral angles are rounded, and the distal border 

 shows in the middle a rather broad lobe which projects into the 

 interradial space. The adoral plates are elongated and narrow, 

 broader without than within, and they give off a rather thick lobe, 

 which separates the mouth shield from the first side arm plate. 

 The oral plates are triangular and low. The mouth papillae number 

 five on each side ; the four internal are conical and subequal, although 

 the fifth, or external, papilla is very broad, rectangular, and very 

 much broader than long. The terminal unpaired papilla is broad 

 and short, rounded, and very much thicker than the neighboring 

 papillae. 



The upper arm plates, which are of medium size, are triangular, 

 half again as broad as long, with the distal border rounded ; they are 

 separated by a narrow interval. 



The first under arm plate is quadrangular or pentagonal, with a 

 very obtuse proximal angle bordered by two straight sides; some- 

 times this angle is so obtuse that it disappears completely ; the lateral 

 borders are straight, and the distal edge is broad and somewhat 

 rounded ; this plate is broader than long. The following plates are 

 large, pentagonal, broader than long, with an obtuse proximal angle, 

 the sides excavated by the tentacle scale, which is very large, and a 

 convex distal border. These plates are in contact for almost the 

 whole of their length in the specimen from station 5348, but in the 

 other they are separated by a very narrow interval. 



The side arm plates, which are rather projecting, bear six spines, 

 the length of which increases from the first ventral, which is almost 



