OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 57 



The side arm plates are moderately developed and cover half 

 the length of the segments. The} 7 are projecting and carry eight 

 spines, increasing in length from the first ventral, which is a little 

 shorter than the segment, to the antepenultimate dorsal, which is 

 as long as three segments; the last spine is usually a little smaller 

 than that preceding. The two lateral rows of spines are very close 

 together in the dorsal median line of the arms, though without 

 forming a continuous series. The spines are slightly flattened, and 

 the ventral are provided with rather strong and sharp denticula- 

 tions which become much smaller and less apparent on the dorsal; 

 these last may even be entirely smooth. 



The under and side arm plates show on their surface rather well- 

 marked parallel striations. 



The tentacle scale, always single, is of medium size ; it is at first 

 oval and rather broadened, beyond the disk becoming pointed; its 

 surface is somewhat rugose, especially toward the point, though 

 without becoming spiniferous. 



The color in alcohol is a light brownish pink. 



The single specimen was taken at a depth of only 90 meters (49 

 fathoms) ; Lyman's type, which came from Cebu, was dredged in 174 

 to 183 meters (95-100 fathoms). 



OPHIACANTHA PACATA, new species. 



Plate 18, figs. 1, 2, 3. 



Locality. — Albatross station 5589; Sibuko Bay, Borneo, and vicin- 

 ity; Nabul Island (NW.) bearing N. 3° W., 5.19 kilometers (2.8 

 miles) distant (lat. 4° 12' 10" N., long. 118° 38' 08" E.) ; 475 meters 

 (260 fathoms) ; September 29. 1909 ; f ne. gy. S., gy. M. 



One specimen (Cat. No. 41234, U.S.N.M.*). 



Description. — The diameter of the disk is 12 mm., and the arms 

 are 45 mm. long. 



The disk is rounded. The dorsal surface is covered with extremely 

 thin and translucent plates not entirely concealing the underlying 

 tissues, which form a very dark mass. These scales become very 

 much smaller and very much more transparent toward the periphery 

 of the disk in the interradial spaces. Each of these carries a strong 

 and elongated similarly translucent spine, of which the base is 

 broadened, but which tapers rapidly into a slender cylindrical stem, 

 this again enlarging toward the extremity and at the same time 

 becoming flattened. This broadened and flattened terminal part 

 bears on its sides one or two short, conical, and pointed teeth of very 

 variable shape and size, and sometimes absent altogether. The 

 smaller interradial plates about the periphery of the disk are with- 

 out spines. The radial shields are visible; they are small and tri- 



