208 BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



Side arm plates large, meeting broadly above and more or less below; 

 each plate carries nine long, slender, nearly smooth arm spines, of 

 which the uppermost (or next to it) is the longest, and may equal 

 fully four joints; on the basal joints of the arm, the spine series of 

 opposite sides meet immediately behind the upper arm plate; this 

 union of the spine series is most marked on the first three joints 

 distal to the disk, but at no point on the arm are the series of any one 

 joint as far apart as the width of an upper arm plate. Tentacle scale 

 single, of moderate size, flat, oval, and sharp. Color (dried from alco- 

 hol), nearly white, but with a yellowish tinge. 



Locality. Albatross station 4957, off southern Japan, lat. 32 36' 

 N.; long. 132 23' E., 437 fathoms, green-brown mud, fine gray sand, 

 foraminifera, bottom temperature 39.8, 2 specimens. 



Type.C&t. No. 25741, U.S.N.M., from station 4957. 



I was at first inclined to consider these specimens as representatives 

 of 0. duplex Kcehler, but further study has satisfied me they can not 

 be that species. It does not seem necessary, however, to give figures, 

 the relationship with duplex is so marked. The essential difference 

 is in the number and arrangement of the arm spines; in duplex (10 

 mm., disk diameter) .there are eight, and, except the first basal series, 

 they are not approximated dors ally, but are separated by the full 

 width of the upper arm plates; in diploa (7 mm., disk diameter) there 

 are nine, and the series are closely approximated dorsally immedi- 

 ately behind the upper arm plates. Moreover, while the spines in 

 diploa are nearly smooth (rough under a magnification of eight diame- 

 ters) and the longest are equal to fully four joints, Koehler says of 

 duplex, "piquants garnis de denticulations assez fortes; le premier 

 ventral est plus long que Particle, le dernier dorsal est plus long que 

 deux articles." The oral papillae in diploa seem to be much more 

 slender, and sharper than those of duplex, and the under arm plates 

 are very different. The combination of these characters has per- 

 suaded me to distinguish diploa as a new species. 



OPHIACANTHA INUTILIS. 



Ophiacantha inutilis KCEHLER, Siboga Oph. Mer Prof., 1904, p. 111. 



Localities. Albatross station 49 19, Eastern Sea, lat. 3034' N.; long. 

 129 19' 30" E., 440 fathoms, globigerina ooze, bottom temperature 

 41.8, 1 specimen; station 4965, off eastern Japan, lat. 33 35' 20" N.; 

 long. 135 10' 50" E., 191 fathoms, dark green-gray sand, shells, bot- 

 tom temperature 49.4, 1 specimen; station 5091, Uraga Strait, lat. 

 35 4' 10" N.; long. 139 38' 12" E., 197 fathoms, green mud, coarse 

 black sand, pebbles, bottom temperature 47.6, 1 specimen; station 

 5092, Uraga Strait, lat. 35 4' 50" N.; long. 139 38' 18" E., 70 

 fathoms, coarse black sand, bottom temperature 56.3, 1 specimen. 



