OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 149 



One specimen (Cat. No. E.325, U.S.N.M.). 



Albatross station 5541; Tagolo Light bearing S. 65 W., 23.54 

 kilometers (12.7 miles) distant (lat. 8 49' 38" N., long. 123 35' 30" 

 E. ; 400 meters (219 fathoms) ; August 20, 1909; fne S., brk. Sh. 



Two specimens (Cat. No. E.322 U.S.N.M.). 



Albatross station 5543; Tagolo Light bearing. S. 75 W., 23.16 

 kilometers (12.5 miles) distant (lat. 8 47' 15" N., long. 123 35' 

 00" E.) ; 296 meters (162 fathoms) ; August 20, 1909; S. 



Four specimens (Cat, No. E.321, U.S.N.M.). 



Notes. The study of the very fine series of specimens collected by 

 the Albatross has convinced me that 0. polyploca, described by H.L. 

 Clark in 1911 and met with in various localities in the Japanese seas 

 between 85 and 152 fathoms, can not be separated from O. rugosa, 

 which I described in 1904 from specimens collected by the Siboga in 

 the Sunda Archipelago, and I am convinced that the two in reality 

 represent only a single species which shows very considerable varia- 

 tion. 



H. L. Clark characterized his 0. polyploca by the radial shields of 

 very large size covering the major portion of the dorsal surface of the 

 disk, by the dorsal arm spines, which are very long and smooth, and 

 by the small mouth shields, which are provided with a narrow and 

 elongated distal lobe projecting into the interradial space. In his 

 description he states that the upper arm plates have the distal border 

 furnished with fine spinules, that the under arm plates show a 

 rounded and projecting distal lobe which beyond the first segments is 

 furnished with rugosities or spines, of which the number little by 

 little increases. 



Almost all the Albatross Philippine specimens show the same form 

 of mouth shield, and this form is identical with that which H. L. 

 Clark has described and figured ; it may be recognized on the photo- 

 graphs which I give here (pi. 28, figs. 2, 5). The elongation of the 

 distal lobe is more or less marked, and the principal part of the 

 shield itself is sometimes very small, but sometimes, on the other 

 hand, relatively rather large; in the specimen from station 5167, 

 shown in figure 2, this part is of medium size, and it is often smaller, 

 while in the specimen from station' 5187, represented in figure 5, it 

 is larger. In the specimen from station 5275 (pi. 27, fig. 6) the 

 mouth shields are appreciably larger than usual, and their distal 

 lobe is less accentuated. This form recalls that which I had noticed 

 among the Siboga specimens; I stated in my description that these 

 mouth shields are small, triangular, with a distal lobe which may 

 become rather prominent and give them a lozenge-shaped form, 

 though this lobe remains ordinarily rather broad and short ; I notice, 

 however, that on one of the specimens from station 254 this lobe 



