OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 391 



are elongated and become smaller and smaller, except for the last 

 which is a little larger than the preceding; the unpaired terminal pa- 

 pilla is larger than those on either side, and conical. 



The two first upper arm plates are short and transversely broad- 

 ened. The first is quadrangular, and the second, which is in con- 

 tact with the first, is triangular with a distal angle. The following 

 plates are small, lozenge-shaped, longer than broad, and widely sepa- 

 rated; they become smaller and smaller, although they persist 

 throughout the whole preserved portion of the arms. 



The first under arm plate is very small, pentagonal, a little broader 

 than long; the three following are large, triangular, with a sharp 

 proximal angle, the sides excavated by the tentacle pore, and the 

 distal border slightly convex. The second plate is almost in contact 

 with the third, and the fourth is separated from the preceding. Be- 

 yond the disk the plates become very much smaller, and they are 

 widely separated ; they are triangular, a little broader than long, but 

 they persist throughout the whole preserved portion of the arms. 



The side arm plates carry at first six small and short spines, the 

 number then falling to five, and later to four. 



The tentacle pores number three pairs ; those of the first pair are 

 very large and resemble those of an Ophiura; they carry three large 

 scales on each of their borders. The two following pores are still 

 very large ; those of the second pair have two or three internal scales, 

 and one or two external scales ; those of the third pair have two in- 

 ternal and one external scales. 



The color of the specimen in alcohol is yellowish. 



Affinities and distinctive features. — Ophiomusium armatum is 

 especially close to O. drmigerum Lyman; it is distinguished from it 

 by having the dorsal plates of the disk more uniform, without the 

 least indication of primary plates, by having the radial shields 

 smaller, by having the upper arm plates also smaller, by the slightly 

 different form of the mouth shields, by the development of the ten- 

 tacle pores, especially those of the first pair, as well as by the number 

 of scales which they bear on each border, and by having the arm 

 spines slightly more numerous. 



OPHIOMUSIUM ELEGANS Koehler. 



Plate 88, figs. 1-9. 



Ophiomusium elegans Kcehleb ('96), p. 305, pi. 6, figs. 22, 23; ('99), p. 23, 

 pi. 3, figs. 22-24; ('04), p. 66.— H. L. Clark ('15). p. 334. 



Localities. — Albatross station 5127; Sulu (Jolo) Sea, in the vicinity 

 of southern Panay; Nogas Island (W.) bearing N. 11° 30' E., 40.77 

 kilometers (22 miles) distant (lat. 10° 02' 45" N., long. 121° 48' 15" 

 E.) ; 1,752 meters (958 fathoms).; February 4, 1908; gy. M., Glob. 



Two specimens (Cat. Nos. 40995, 40997, U.S.N.M.). 



