136 



BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



gular, with rounded angles, wider than long, somewhat variable. 

 Side mouth shields large, nearly horizontal, much wider without than 

 within. Oral papillae single in outer corner of mouth angle, large, 

 flat, and wing-shaped. Teeth notched so that some of the lower ones 

 seem to have three points. Genital slits broad and conspicuous. 

 First under arm plate small, triangular, with a distal angle or 

 tetragonal with distal margin narrow; succeeding plates more or less 

 hexagonal (or tetragonal) with rounded angles, wider than long, 

 scarcely or not at all in contact, though the side arm plates do not 

 meet between them at base of arm. Side arm plates large, meeting 

 below and above on distal part of arm; each plate carries three mod- 

 erately stout spines, 

 uppermost longest and 

 longer than an arm 

 joint. Tentacle scales 

 single, large, oval. 

 Color (dried from alco- 

 hol), very light yellow- 

 ish, grayish, or nearly 

 white. 



Localities. Albatross 

 station 3697, off Mana- 

 zuru Zaki, Honshu Is- 

 land, Japan, 120 to 265 

 fathoms, gray mud, 

 volcanic sand, 1 speci- 

 men; station 4956, 

 southeastern Japan, 

 lat. 32 32' N.; long. 

 13225 / E.,720fathoms 

 green-brown mud, fine 

 gray sand, foraminif- 

 era, bottom tempera- 

 ture 37.5, 1 specimen; 

 station 4957, southeastern Japan, lat. 32 36' N.; long. 132 23' E., 

 437 fathoms, green-brown mud, fine gray sand, foraminifera, bottom 

 temperature 39.8, 2 specimens. Bathymetrical range 120 to 720 

 fathoms. Temperature range 39.8 to 37.5. Four specimens. 

 Type. Cat. No. 25602, U.S.N.M., from station 4957. 

 The specimen from station 3697 measures 9 mm. across the disk. 

 It differs from the type in having the radial shields separated even at 

 the tip, the upper arm plates are lower and wider, and both the upper 

 and under arm plates seem to be nearer together. There are a very 

 few short spines at margin of disk and below, and in several of the 

 mouth angles a small second oral papilla is distal to the large one. 



FIG. 51. OPHIACTIS BRACHYGENYS. XlO. a, FROM ABOVE; 6, FROM 

 BELOW; c, SIDE VIEW OF TWO ARM JOINTS NEAR DISK. 



