OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 255 



(pi. 41, figs. 7, 8), two photographs of a specimen from Amboina, the 

 one which I described in 1904 (Koehler '04a, p. 110). 



Ophiothrix pavida may be also compared with O. armata Koehler, 

 but it is immediately distinguished by its smaller radial shields which 

 are covered with spines, by the entirely different form of the upper 

 and under arm plates, by the more slender arm spines, and by the 

 coloration. It differs still more from O. virgata Lyman in having 

 its radial shields in contact outwardly, in its longer arm spines, in 

 the form of the upper and under arm plates, and in the coloration, 

 which is entirely different. 



OPHIOTHRIX PLANA Lyman. 



Plate 38. figs. 3-5 ; plate 101, fig. 2. 



See for bibliography : 

 Ophiothrix plana Koehler ('05), p. 75. — H. L. Glark ('15), p. 276. 



Locality. — Albatross station 5179; vicinity of Romblon; Romblon 

 Light bearing S. 56° E., 8.34 kilometers (4.5 miles) distant (lat. 12° 

 38' 15" N., long. 122° 12' 30" E.) ; 68 meters (37 fathoms) ; March 

 25, 1908; hrd. S. 



One specimen (Cat. No. 41015, U.S.N.M.). 



Notes. — The single specimen collected by the Albatross agrees very 

 well with Lyman's type, and the dorsal surface of the disk is quite 

 naked, as may be seen on the photograph which I give of it (pi. 38, 

 fig. 3). In 1905 I described the variations which this species shows 

 in the armature of the disk, and I include (fig. 4) a figure of the 

 dorsal surface of a specimen from the Sunda Islands in which the 

 dorsal plates of the disk bear small conical granules. 



In the Albatross specimen the adoral plates are very widely sepa- 

 rated from each other; they broaden very much outwardly, and are 

 continued by a very broad distal lobe separating the mouth shields 

 from the first side arm plate. The distal border of the first under 

 arm plates is at first slightly convex and rounded, becoming beyond 

 the disk rather strongly excavated. 



The hook formed by the first ventral arm spine shows the usual 

 form with two or three branches which are always well developed 

 (pi. 101, fig. 2a). The tentacle scale ends in a conical point which 

 is rather broad at the base (fig. 2b). 



The coloration of the specimen is pinkish gray on the dorsal sur- 

 face of the disk and of the arms, as well as on the ventral surface of 

 the latter; the ventral surface of the disk is a very dark brown in 

 those portions which are not covered with spines. 



Ophiothrix plana is a littoral species which has been found in a 

 number of localities in the Indian Ocean ; the Siboga met with it at 

 various depths, from the surface down to 54 meters (30 fathoms). 



