NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 225 



stumps; how numerous the stumps normally arc the present condi- 

 tion of the specimen iloes not permit us to determine. Radial shields 

 exposed only at the extreme distal ends where they are not quite in 

 contact. Upper arm plates triangular, as long as wide or longer, 

 widely separated; arms decidedly constricted between each pair. 

 Interbrachial space below like disk above. Genital slits large. Oral 

 shield broadly pentagonal, much wider than long; distal side very 

 short. Adoral plates moderate, three times as long as broad, meeting 

 very narrowly within. Oral papillae three on a side and one at apex 

 of jaw, long, thick, bluntly pointed; distal papilla much the widest. 

 (In fig. 104& the distal papilla is drawn in an oblique position, so that 

 its full width is not indicated.) First under arm plate longer than 

 wide, rather hexagonal; succeeding plates more or less pentagonal, 

 at first much wider than long, but soon becoming longer than wide, 

 well separated. Side arm plates low and long, but meeting broadly 

 both above and below; each plate carries six smooth, slender spines, 

 of which the next to the uppermost is longest and may equal two 

 joints. Tentacle scale single, quite large, oval, flat, and blunt. 

 Color (dried from alcohol), dirty whitish, the disk with a decidedly 

 gray tinge. 



Locality. — Albatross station 3338, off Alaska, lat. 54° 19' N.; long. 

 159° 40' W., 625 fathoms, green mud, sand, bottom temperature 

 37.3°, 1 specimen. 



Type.—Cat, No. 25529, U.S.N.M., from station 3338. 



This is one of those exasperating specimens which, although without 

 any distinctive or notable characters, refuse to be assigned to any 

 known species, and yet are so small and. badly preserved it is humilia- 

 ting to make them types of new species. Although other species of 

 Opliiacantlia were taken at station 3338, this specimen can not be 

 referred to any one of them, and I do not know of any species from 

 elsewhere with which it might be united. 



OPmACANTHA EUPHYLACTEA, new species.a 



Disk 7 mm. in diameter; arms about 35 mm. long. Disk covered 

 by a fine scaling (coarse near radial shields), which was probably 

 concealed in life by the minute, thorny stumps, of which there are 

 now only a few scattered ones left. Distal ends of radial shields 

 exposed and nearly in contact. Upper arm plates rounded pentag- 

 onal or hexagonal, at first wider than long, but soon becoming as 

 long as wide. Although not actually in contact, they separate the 

 side arm plates widely. Interbrachial space below like disk. Geni- 

 tal slits very large. Oral shield tetragonal, with wide proximal 



" Eu, Signifying well, and (j)oXaKT£oc, signifying guarded, in reference to the way in 

 which the lower arm spines prelect the tentacles. 

 34916°— Bull. 75—11 15 



