6a natural history bulletin. 



Opiiiochondrus gracilis Verrill, sp. now 



Disk small; arms long and slender,' tapering but little, coiled. 

 Upper arm-plates small, thick, slightly in contact with each 

 other, broad ovate, "top-shaped." or subtriangular with round- 

 ed angles, about as broad as long on the proximal half of the 

 arm; outer end strongly convex, lateral angles rounded, ob- 

 tuse; on the distal part of the arm they become more triangu- 

 lar or somewhat heart-shaped, and are separated by the side 

 plates, under arm-plates small, thick, except the basal, broad- 

 triangular, with rounded angles and convex outer edge, about 

 as long as broad, separated by the side plates; the distal end 

 is thick and raised. Tentacle-scale one. large for the genus, 

 oblong-ovate or short spiniform, obtuse. Arm-spines eight. 

 on the greater part of the arm short, stout, a little flattened, 

 rather obtuse, slightly rough, nearly equal in length, or the 

 uppermost a little longer than the others; distally they be- 

 come more slender and tapered; near the base of the arm, on 

 some of the joints, the upper spine is often twice as long as 

 the others, tapered and acute. 



Oral shield small, thick, pear-shaped, with an acute inner 

 angle, as long as broad. 



Adoral shields large, thick, and rough like the oral shields, 

 pear-seed shaped, the inner ends prolonged, acute, and largely 

 joined. Mouth-papillae three on each side and an odd term- 

 inal one; they are relatively large, prominent, not crowded, 

 obtuse, the outer one slightly flattened. The upper surface 

 of the disk is destroyed. 



Diameter of disk-scar, 3 mm; diameter of arm, without 

 spines, 80 mm; length of arms, imperfect at tip, 20 mm. 



Off Havana, no to 260 fathoms, on gorgonians, two ex- 

 amples. 



This species, although the covering of the disk is unknown, 

 differs very decidedly from all those hitherto described in the 

 slenderness and length of the arms; elongated upper arm- 

 spine on the proximal joints; form of arm-plates, tentacle- 

 scales, mouth-papillae, and oral shields. 



