OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 27 



pieces, as well as the muscles between them, can be distinguished 

 through it (figs. 16, 17). The side arm plates are especially de- 

 veloped on the ventral side ; each forms a large swelling (figs. 5, 6, 17) 

 on which are implanted the arm spines and which are continued onto 

 the ventral surface in the form of a narrow process; this adjoins its 

 fellow in the median line of the arm by a rounded border (fig. 6). 

 The arm spines are five in number and are in the form of compound 

 hooks; the central spines carry usually five or six short, conical, and 

 pointed teeth the size of which decreases toward the tip, while the 

 dorsal and ventral spines as a rule have only four teeth of which the 

 last is often the most developed. As previously stated, the tentacular 

 pores are very small. 



The general coloration of the individual is dorsally a dark choco- 

 late brown and ventraily a little lighter. 



OPHIOBYRSELLA INTORTA. new species. 



Plate 4, figs. 2-5 ; plate 92, fig. 4. 



Locality. — Albatross station 5491; between Leyte and Mindanao; 

 Diuata Point (W.) bearing S. 9° W., 35.77 kilometers (19.3 miles) 

 distant (lat. 9° 24' 00" K, long. 125° 12' 00" E.) ; 1,346 meters (736 

 fathoms) ; August 1, 1909; gn. M., Co. 



One specimen (Cat. No. E. 331, U.S.N.M.). 



Description. — The disk is somewhat deformed through being 

 strongly pulled out along one of the rays, on account of which it 

 measures 30 mm. in the longest diameter but only 20 mm. in the 

 shortest; presumably in the living animal it had a diameter of be- 

 tween 22 mm. and 24 mm. The arms are very long and rather nar- 

 row, especially in their distal half, where they become extremely 

 slender; their length is difficult to judge, as they are more or less 

 strongly rolled up, but it must be between 250 mm. and 300 mm.; 

 they are 3 mm. broad at the base. They are almost cylindrical, with 

 the ventral face slightly flattened. 



In the living animal the disk must have been slightly concave in 

 the interradial spaces, just as between the two radial shields of each 

 pair above the insertion of the arms. The dorsal surface is covered 

 by a thin integument studded with extremely small plates well sepa- 

 rated from each other and each bearing a very short and slender 

 spinelet; to the naked eye these spinelets appear as simple little 

 points, which are especially evident through their white coloration, 

 which causes them to stand out in sharp contrast against the dark 

 brown integument of the disk. The integument is raised over the 

 radial shields into elongated ridges which are white in color. The 

 radial shields are narrow, elongated, broadened outwardly, and taper- 

 ing gradually toward the center of the disk; they are about 7 mm. 



