130 Bulletin VanderbUt Marine Mitseum, Vol. VII 



4), itself a cluster of green and white feathery fronds, as to be 

 invisible, the small serpent-star disks very closely resembling the 

 globular female gonotheca of the hydroid, and the serpent-star 

 arms intertwined among the branching hydroid fronds. The small- 

 est of these ophiurans have a disk diameter of about 2 millimeters 

 and the largest ones are from 3 to 4 millimeters diameter. All are 

 regularly six-armed. 



Delicately entwined among the arms of a serpent-star and 

 hydroid frond, and so closely resembling the ophiuran arm as to 

 be mistaken for it, there was found a Polychaete Annelid, the 

 metameric segmentation and parapodia effecting perfect mimicry 

 of the joints of the brittle-star arm and arm-spines. 



Technical description : The largest of the three specimens 

 from Raiatea Island has the disk diameter of 4 millimeters and an 

 arm length of about 16 millimeters. The disk is circular, moder- 

 ately thick and has the greater portion of its surface covered with 

 six pairs of large, cordate radial plates, the apices of which are 

 directed inward and reach nearly two-thirds of the radius of the 

 disk. The plates of a pair of radialia are each pear-seed shape, 

 stout, adjacent proximally and with the inner tapered third a 

 little separated by a row of small scales. The outer lateral margin 

 of the radial plate is more rounded than the inner margin, and 

 the distal or outer margin is sinuate, being produced to a rounded 

 peak on the inner half. The center of the disk, interradial areas 

 and lateral margins are paved with small, suboval, subcircular 

 and irregular scales. The circumferal margin of the disk is beset 

 with coarse, stout, conical spines, set well apart and having their 

 tips beset with small hooks. Less frequently these spines occur 

 near the center, along the median radius line of the interbrachial 

 area and along the outer margin of the radial plates and at or 

 almost on the apices of the radial plates. The actinal surface of 

 the disk is paved with small scales similar to those of the abactinal 

 surface. 



The central mouth shield is wide suboval, with the outer 

 margin widely convex and the inner margins oblique, converging 

 to a subacute apex. The adoral shields are triangular, with the 

 narrowed apices meeting within, the inner distal angle adjacent 

 to central plate and the outer distal angle rounded and touching 

 the minute first under arm plate. There are two, more rarely 

 three, small, squarish mouth papillae on either side of the jaw 



