228 BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



Interbrachial spaces below covered with scales, carrying a few elon- 

 gated granules. Genital slits small. Oral shields rhombic, with 

 rounded angles, about as long as wide. Adoral plates very large, 

 about half as wide as long, meeting broadly within. Oral papillae 

 large, three on a side and one at apex of jaw, bluntly pointed, sub- 

 equal, or distal one largest. Under arm plates wider than long, the 

 first about half as large as second; first and second distinctly in 

 contact, second and third hardly so, the remainder separated. Side 

 arm plates rather large, meeting above and below, except at very 

 base of arm. Each plate carries eight stout spines, of which the 

 second or third (from above) is the longest, equaling two joints or 

 more; uppermost three and lowest one smooth, the intermediate 

 four slightly rough near tip. Tentacle scale single, large; broad and 

 rounded on basal pores, it soon becomes narrower and pointed. 

 Color (dried from alcohol), light grayish-brown. 



Locality. Albatross station 5084, off OmaiSaki Light, lat. 34 N.; 

 long. 137 49' 40 " E., 918 fathoms, green mud, fine sand, globiger- 

 ina, bottom temperature 36.8, 1 specimen. 



Type.C&t. No. 25593, U.S.N.M., from station 5084. 



This single specimen, which is very well preserved, is much like 

 cataleimmoida, except in the oral shields and adoral plates and in 

 the disk covering. In the latter particular, it is quite unlike any 

 other Ophiacantha in the collection, and I fail to find any previously 

 known species to which it might be referred. 



OPHIACANTHA ATOPOSTOMA, new species." 



Disk 10 mm. in diameter; arms probably about 50 mm. long. 

 Disk covered by numerous slender pointed spines, one-fourth to one 

 millimeter long, which under a microscope are minutely thorny. 

 Radial shields only visible distally, where they are well separated 

 and surrounded by the disk spines. Upper arm plates triangular, 

 with distal side convex, wider than long and well separated. Inter- 

 brachial spaces below much like disk above. Genital slits small. 

 Oral shields rounded, wider than long, with distal side more or less 

 projecting. Adoral plates large, twice as long as wide, meeting 

 broadly within. Oral papillae five or six on a side (sometimes a single 

 one at apex of jaw), the proximal ones narrow and pointed, the distal 

 one (outermost) broad, flat and rounded at tip; distal to this broad 

 papilla and borne on the proximal edge of the adoral plate, is a sharp, 

 slender, spinelike papilla (sometimes there are two). First under 

 arm plate small and squarish, a trifle wider than long; second plate 

 in contact with first, heptagonal, wider than long; third barely touch- 



<* "Armor, signifying odd, peculiar, and arfyta, signifying mouth, in reference to the 

 peculiar mouth parts. 



