OPHirEOIDEA FEOM THE KOEEAN SEAS. 



461 



The mouth- shields are small and granular ; they are broader 

 than long, rounded without, angular within, where a reenter- 

 ing curve slopes to the rounded, but angular, sides. The 

 madreporic is the largest. The side mouth-shields are large, 

 and rather long and rectangular in shape j they reach on to the 

 lower arm-plate. 



The jaws are broad and short; the mouth- papillae are large, 

 thin and rounded, and there are six to each angle. Beneath 

 the lowest tooth there is a broad rounded knob separating the 

 papillae. The teeth are ten or eleven in number, increasing in 

 length and breadth from below upwards ; they are straight or 

 slightly guttered within. The jaw-plates are well-defined, and the 

 lowest teeth form a funnel-shaped cavity leading to the close 

 upper ones. 



The lower arm-plates. — The first is rudimentary, and is bounded 

 on either side by the very close ends of the side mouth-shields : 

 the second is large, and the general shape is much broader than 

 long ; the inner edge is grooved and concave; the outer, the longest, 

 is nearly straight or slightly concave. The sides are slightly 

 incurved for the tentacle-scale, and the corners are slightly 

 rounded. The plates are separate; and the union is by a skin, 

 the side arm-plates not reaching between. Near the tip the 

 plates become longer and are still separate. 



The side arm-plates are small, project from the side of the arm, 

 have four short spines on the edge, and a large tentacle-scale 

 which extends along the side of the lower arm-plate. The spine 

 next to the scale is the smallest, and becomes a three-spined 

 hook near the tip of the arm. The spines are conical, broad 

 below, bluntish, are faintly striated, and stand out from the 

 arm. The surface of the lower arm-plates is granular, and there 

 are indications of faint rings of colour on the arms. 



The upper arm-plates are surrounded by a row of very small 

 accessory plates, fourteen to eighteen in number; there is a 

 large accessory plate at the side and rather without, where it 

 simulates in size and position part of the side arm-plate ; it is 

 bounded, but not externally, by small accessories. The upper 

 arm-plates nearest the disk are small and more or less rudimen- 

 tary, are broader than long, and they are crowded by the rows 

 of small accessory scales : after the fourth or fifth, the others 

 become large, oval from side to side, and much broader than long. 

 In some specimens one of the edges is often straiglit. Further 



