NORTH PACIFIC OPHTURANS IN NATIONAL MUSEUM — CLARK. 137 



The adoral plates arc broadly in contact both radially and interradi- 

 ally and so make a continuous circumoral rino;, as in Ilemipholis. The 

 principal difference between this species and the preceding is in the 

 number of arms, but this striking difference is associated with several 

 minor ones, such as the form of the oral shields and adoral plates, the 

 length of the arm spines, and the color. 



OPHIACTIS DYSCRITA, new species, a 



Disk 2.5 mm. in diameter; arms about 10 mm. long. Disk cov- 

 ered with about one hundred and fifty coarse scales. Radial shields 

 long and narrow, separated, except at distal ends, by a single wedge- 

 shaped scale. Arms six, not very attenuate. Upper arm plates 

 somewhat pentagonal (or hexagonal) much wider than long, with 

 lateral angles rounded, more or less in contact with each othei-, on 



Fig. 52.— Ophiactis dtscrita. X20. a, from above; 6, from below; c, side view of two arm joints 



NEAR DISK. 



basal half of arm. Interbrachial spaces below closely scaled. Geni- 

 tal slits rather conspicuous. Oral shields oval or ovoidal, about as 

 long as wide or a little shorter. Adoral plates large, not meeting 

 within, enlarged at outer ends. Oral papilla^, single, on each side 

 of mouth angle, small and flat. First under arm plate small, longer 

 than wide, narrowed distally; succeeding plates more or less pentag- 

 onal, about as wide as long, more or less in contact on basal part of 

 arm. Side arm plates moderate, meeting above and below on distal 

 half of arm; each plate carries three spines, of which the middle one 

 is longest or at least as long as the uppermost, and equals the joint. 

 Tentacle scales single, moderately large, oval. Color (dried from 

 alcohol), gray. 



« J'jaKp:zoc, sip^nifyins; hard tn determine, in reference to the doubtful value of the 

 specific characters. 



