OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 241 

 OPHIOTHRIX INFIRMA Koehler. 



Plate 48, figs. 5, 6, 7 ; plate 100, fig. 1. 



Ophiothrix infirma Kcehler ('05), p. S9, pi. 8, figs. 10-13. — H. L. Clakk 

 ('15), p. 281. 



Locality. — Albatross station 5153; Sulu (Jolo) Archipelago, Tawi 

 Tawi Group, Tocanhi Point bearing S. 27° E., 3.89 kilometers (2.1 

 miles) distant (lat. 5° 18' 10?' N., long. 120° 02' 55" E.) ; 90 meters 

 (49 fathoms) ; February 19, 1908 ; co. S., Sh. 



Two specimens (Cat. No. E. 12, U.S.N.M.). 



Notes. — The two specimens are in fairly good condition, especially 

 one of them, which is almost complete and which I have shown on 

 plate 48 as figures 5-7 ; the disk measures 11 mm. in diameter. The 

 other specimen is a little larger. 



The radial shields are very large, almost completely naked, and 

 separated by a narrow interval. The interradial spaces are relatively 

 narrow. The dorsal plates of the disk have fairly distinct outlines, 

 and bear small and very numerous club spines terminated by a few 

 short spinules which are rather obtuse, unequal, and erect (pi. 100, 

 fig. la) , without the least indication of true spines. As I said in de- 

 scribing the species in 1905, the tentacle scale is very large (fig. Id) ; 

 it is rounded, with a few slightly developed asperities on its free 

 border. The first ventral spine beyond the proximal third of the 

 arms assumes the form of a three branched hook which is very 

 large and strongly developed (fig. 1c). The two distal branches of 

 the hook are especially well developed, but the third is very much 

 less so; often a more strongly curved fourth point is added toward 

 the base of the hook. 



The coloration of the two specimens is pink. A white line extends 

 throughout the whole length of the dorsal surface of the arms 

 broadening and narrowing on each group of three or four segments ; 

 it is bordered on either side by a dark purple line which toward the 

 distal border of each upper arm plate forms a very pronounced spot; 

 another dark spot, somewhat smaller, lies at the base of the last dorsal 

 spine. The ventral surface of the arms shows a broad white line 

 outside of which the general coloration is pink, and there is also on 

 each side of the white line a dark purple spot toward the distal 

 border of the under arm plate. 



In discussing the characters of O. infirma in 1905 I compared it 

 with O. stelligera Lyman, from which I said it is distinguished by 

 having its radial shields in part naked, by having the arm plates 

 larger, and especially remarkably broad, and by having the tentacle 

 scale very large and rounded. The affinity of these two species is still 

 55269— 22— Bui. 100 1G 



