122 BULLETIN 84, UNITED STATES NATIONAL MUSEUM. 



West Coast of Florida. One specimen. 



Bahamas. Twenty-two specimens. 



Belize, British Honduras. One dry specimen. 



Bermudas. Two specimens. 



Green Cay, Bermudas. One specimen. 



OPmOTHRIX CONVOLUTA, new species. 

 Plate 16, figs. 1 aud 6. 



A specimen found on a branch of Acanihogorgia fusca, without any indication 

 of locality. 



Type— Cat. No. 32303, U.S.N.M*. 



The diameter of the disk reaches 6 mm.; the arms are strongly convoluted 

 and their length must have exceeded 45 mm. 



The disk is subpent agonal. The upper face offers, between the radial shields, 

 a covermg of rounded and very unequal plates, some of which are small and com- 

 paratively few, the others rather large. The former are unarmed or each of them 

 carries only a Uttle short and thick stump, the others, on the contrary, are provided 

 with a very strong spine which is thick, elongated, and bears, on its edges, strong, 

 sharp, and approximated deuticulations. These spines vary m length, but most of 

 them reach, or even exceed, one millimeter. They are numerous and dense m the 

 central region of the disk and in the interradiil spaces. These spaces are very 

 broad, while the radial spaces, narrow between the two shields of each pair, give 

 the appearance of as many very narrow* triangles, which separate the shields on 

 one-half or two-thirds of their length. The plates which cover these mterradial 

 spaces are small, and they carry only short stumps or even remain absolutely bare. 

 The fairly large radial, shields are triangular and their length exceeds half the radius 

 of the disk; they are twice and a half longer than wide and their radial side is about 

 straight, while the interradial side is strongly convex; their surface is absolutely 

 deprived of spines and covered with mmute granules. The two shields of each 

 pair are little diverging; they are contiguous outwardly for a variable length and 

 they are inwardly separated by the narrow radial areas which I have mentioned 

 above. 



The plates of the upper face and the large spines on them cease at the edge of 

 the disk and the under face is almost completely bare; there are only in the inter- 

 radial areas a few scarce and isolated plates which are not often seen except at the 

 outline of the disk and each of which bears a small stump. The genital shts and 

 plates are broad and well developed. 



The middle-sized mouth shields arc triangular, with a slightly sharp proximal 

 angle which is limited by straight sides, and a very convex distal side; the latter is 

 sometimes broken up into two sides, which gives to the shields a lozenge-like appear- 

 ance; in one of them the proximal angle is separated from the rest of the plate by 

 a fissure. These shields are as long as wide, or even a Uttle longer than wide; the 

 shield which carries the madreporic pore is very large, oval, and much longer than 

 wide. The adoral plates are small, triangular, hardly contiguous on the median 

 interradial hne by their rounded apex. The papillae of the extenaal sets are elon- 

 gated, fairly large, conical, and pointed; the others, located within the foregoing 

 ones, are much smaller. 



