c6 NATURAL HISTORY BULLETIN. 



Plate III; Figures 4. ^a. 



Disk swollen, covered with rather small, thin, flat, rounded, 

 nearly smooth, naked, imbricated scales. Naked part of 

 radial shields long and narrow, wide apart: the inner ends 

 somewhat divergent; the outer ends a little wider or clavate. 

 Arm-spines seven or eight, slender, of moderate length, the 

 upper ones about as long as a joint, decidedly flattened and 

 tapered distally. nearly opaque, hollow and slightly rough; 

 the two lower ones are longer and larger than the rest, more 

 terete, blunt or truncate, rough or thorny at the tip. The 

 basal rows do not approximate dorsally. 



Upper arm-plates obovate. longer than wide, rather large, 

 outer ends thin, obtusely rounded, sides convex; inner ends 

 obtuse, overlapped by the preceding plate; distally they be- 

 come more nearly square, with rounded angles, and about as 

 long as wide. Under arm-plates shield-shaped, longer than 

 wide, the outer end widest and slightly emarginate in the 

 middle, the lateral edges concave; the inner end angulated 

 and slightly overlapped by the preceding plate. Tentacle- 

 scales on several basal joints two. unequal, elongated, flat, 

 rough, ribbed, and palmate at the end. as if composed of two 

 or more divergent spinules united together; more distally the 

 smaller or outer one becomes short, thorny, and acute, and 

 then disappears, while the larger one becomes spiniform and 

 thorny. 



Oral shields very distinct, four-lobed, -'spade-shaped," 

 with the distal lobe narrow and extending into the interradial 

 area; lateral lobes rounded; sides a little incurved; proximal 

 end obtuse. Adoral shield long and narrow, extending back 

 along the sides of the oral shield and slightly separating it 

 from the side arm-plates. 



Mouth-papillae three or four in a regular row, besides three 

 stouter conical ones that stand a little apart from the rest, in 

 a row at the tip of the jaw. but of these only the middle one 

 seems to be on the dental plate; the distal ones seem to be 

 mostly attached to the adoral plates; they are rather large. 



