238 



BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



as long as wide (except at base of arm) or longer, overlapping or in 

 contact on basal half of arm, but becoming separated distally. Inter- 

 brachial space below with scales, at least near oral shield. Genital 

 slits large. Oral shield as long as wide or longer, rounded heptagonal 

 (in smaller specimen, oral shield rhombic with rounded angles, dis- 

 tinctly wider than long). Adoral plates large, L-shaped, meeting 

 within, completely separating the oral shield from side arm plate (in 

 smaller specimen, proximal or long arm of the L more or less aborted 

 and consequently not meeting within). Oral papilhe five or six on a 

 side, thick, blunt, crowded; distal to them, and attached to adoral 

 plate, are several small spine-like papillae, which are the tentacle 

 scales of the huge oral tentacles (second pair). First under arm 



plate moderate, wider 

 than long and widest 

 proximally ; succeeding 

 plates hexagonal or pen- 

 tagonal, rounded distally, 

 much wider distally than 

 proximally, at first wider 

 than long, but rapidly be- 

 coming much longer than 

 wide ; distal end somewhat 

 swollen and elevated; all 

 the plates except first 

 two well separated from 

 each other. Side arm 

 plates low and moder- 

 ately long, scarcely meet- 

 ing above, until far out on 

 arm, meeting narrowly be- 

 low^ ; each plate carries five 

 or six long, slender, 

 smooth spines, of which the uppermost (or next one) is longest, 

 equaling about two joints. Tentacle pores very large; tentacle scales 

 none. Color (dried from alcohol), whitish. 



Localities. — Albatross station 4969, off eastern Japan, lat. 33° 23' 

 40" N.; long. 135° 33' E., 587 fathoms, brown mud, sand, stones, 

 bottom temperature 38.9°, 1 specimen; station 4979, off eastern 

 Japan, lat. 33° 53' N.; long. 137° 42' E., 943 fathoms, brown mud, 

 fine sand, foraminifera, bottom temperature 36.4°, 1 specimen. 

 Type.—Cat. No. 25596, U.S.N.M., from station 4969. 

 It is both remarkable and unfortunate that the two specimens of 

 this interesting species should have completely lost the disk. But 



Fig. 113.— Ophiacantha megatreta. X 2.25. a, feom be- 

 low; 6, SIDE view of two arm joints near disk; c, upper 

 VIEW of three arm joints near middle of arm. 



