OPHIURANS 01? THE PHILIPPINE AND ADJACENT WATERS. 141 



I described 0. pulchra from specimens in which the diameter of 

 the disk did not exceed 11 mm., and 0. mitis from specimens of large 

 size in which the diameter of the disk reached 18 mm. I distin- 

 guished O. mitis especially by the characters of the dorsal surface 

 of the disk, which is covered by numerous plates provided with 

 rounded, smooth, small, and crowded granules, by the relatively 

 smaller radial shields, by the more numerous arm spines, by the also 

 more numerous mouth papillae, and by the tentacle pores of the first 

 pair, which are furnished with two scales. But if the differences 

 in the armature of the disk were well marked in the Siboga speci- 

 mens, it is by no means the same in those of the Albatross, and it is 

 impossible for me to separate the smaller specimens having more 

 or less the characters of 0. pulchra from the larger in which the 

 characters are those of 0. mitis. 



I do not find in the Albatross collection any specimens with gran- 

 ules quite so large as in those from /Siboga station 297, of which 

 I figured one in 1904 ('04, pi. 27, fig. 6). It is on one of the two 

 individuals from station 5280, in which the diameter of the disk is 

 9 mm., that I find the largest granules; I give here a photograph 

 of the dorsal surface of this specimen (pi. 30, fig. 3). These granules 

 are shown separately and more enlarged in figure 5a, plate 94. It 

 may be seen that their surface is simply rugose. I also show for 

 comparison in figure 5& a granule from one of the Siboga specimens 

 which is a little larger than the preceding and on which the asperi- 

 ties are very much stronger. In the other specimen from the same 

 station, in which the diameter of the disk is a little greater (9.5 mm.) , 

 the granules are very much smaller and more numerous (pi. 30, fig. 

 5) ; the dorsal surface recalls my figure published in 1904 (pi. 27, 

 fig. 5) , but with the granules a little more numerous. It is the same 

 with the specimen from station 5527 in which the diameter of the 

 disk is 9 mm. In the smaller specimens from stations 5664, 5577, and 

 5629, in which the diameter of the disk varies between 6 mm. and 7 

 mm., the granules are a little less large than in the first specimen 

 from station 5280. 



It is not to be supposed that the size of the granules decreases with 

 age; this I have already emphasized in my description of O. pulchra 

 ('04, p. 126). 



As for the two larger specimens from stations 5629 and 5661, in 

 which the diameter of the disk reaches, respectively, 14 mm. and 

 15 mm., they are identical with those from the Siboga collection 

 which I made the types of O. mitis; this last was merely a little 

 larger, the diameter reaching 18 mm. These two specimens also do 

 not differ much from the larger specimen from station 5280 repre- 

 sented in figure 5 on plate 30, except that the granules of the dorsal 



