OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. Ill 



are a little broader than long and are separated from the base of the 

 arm outAvard by an interval which at first is equal to their length and 

 becomes progressively elongated. 



The first under arm plate, which is of medium size, is triangular, 

 with a rounded proximal angle. The following plates are large,:pen- 

 tagonal, very much broader than long, and they occupy the whole 

 width of the ventral surface of the arms. They have a very obtuse 

 proximal angle bounded by two straight sides, two diverging and 

 straight lateral borders, and a slightly rounded distal border; these 

 plates are widely separated from the base of the arms outward. 



The strongly projecting side arm plates carry eight spines at the 

 base of the arms, but this figure diminishes very rapidly; the first 

 ventral spine is shorter than the segment, and the length thence in- 

 creases progressively to the last dorsal spine, which may be as long 

 as three segments, but the relative length of this spine diminishes 

 rapidly. These spines are slender and pointed, and provided with 

 rather well-separated fine denticulations. On the first arm segment 

 the two lateral series of spines come very close together in the median 

 dorsal line and are continuous with each other. 



The single tentacle scale is large, oval, and broadened on the pores 

 of the first pair ; it becomes progressively narrower and elongated on 

 the following segments, though still remaining oval, and finally be- 

 comes spiniform and pointed. 



Affinities and distinctive features. The arrangement of the dorsal 

 plates of the disk and their armature recalls Ophiomitra polyacantka 

 H. L. Clark, but the radial shields of 0. exilis are very much smaller 

 and more separated, the tentacle scale is smaller, the arm spines are 

 less numerous, and the mouth pieces show a very different arrange- 

 ment. Ophiomitra exilis also recalls O. moniliformis Kcehler, but in 

 this the dorsal plates of the disk bear rounded and smooth granules, 

 the mouth shields are almost as long as broad, the outermost mouth 

 papilla is not especially broadened, and the arm spines are less 

 numerous. 



OPIIIOMITRELLA SAGITTATA, new species. 



Plate 27, figs. 1-4, 9 ; plate 95, fig. 4. 



Localities. Albatross station 5621; between Gillolo and Makyan 

 Islands; Makyan Island (S.) bearing N. 54 W. 5.56 kilometers (3 

 miles) distant (lat. 15' 00" N., long. 127 24' 35" E.) ; 545 meters 

 (298 fathoms) ; November 28, 1909; gy. and bk. (m. b.). 



One specimen (Cat. No. 41009, U.S.N.M.). 



Albatross station 5623; between Gillolo and Makyan Islands; 

 Makyan Island (S.) bearing S. 88 W., 13.90 kilometers (7.5 miles) 

 distant (lat. 16' 30" N. ? long. 127 30' 00" E.) ; 497 meters (272 

 fathoms) ; November 29, 1909; fne. S., M. 



One specimen (Cat. No. 41010, U.S.N.M.). 



