4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 98 



In the largest specimen there are 1 1 arm spines just beyond the disk, 

 the number soon falling to 8, later to 7, and then to 6 or 5. On the arm 

 combs beyond the sixth-eighth the lowest spine is in the form of a 

 hook. 



The largest specimens from Albemarle Island have the disk 15 mm. 

 in diameter and the arms 80 mm. long. Some are entirely blackish. 

 In others the arms are narrowly banded with white on about every 

 fourth upper arm plate, and the disk, except for the extreme edge, 

 may be light or even cream-white. 



OPHIOCOMA SCOLOPENDRINA (Lamarck) 



Locality. — Clipperton Island ; shore collecting on rocks south of 

 landing place; July 21, 1938. One specimen (U.S.N.M. no. E.5619). 



Notes. — In this specimen the disk is about 20 mm. in diameter and 

 the arms are about 105 mm. long. The color above is uniform blackish 

 brown, below the same, each under arm plate with a low white triangle 

 of which the long base coincides with the proximal edge of the plate 

 and the apex reaches nearly half way to the distal edge. These white 

 triangles gradually decrease in size and disappear after about a dozen 

 under arm plates. The proximal lower arm spines are tipped and 

 sometimes longitudinally striped with white, and the mouth papillae 

 are broadly tipped with white. The madreporic plate has a large 

 white oval spot of which the outer end touches the distal border. 



OPHIOCOMELLA, n. gen. 



Diagnosis. — A genus of Ophiocomidae in which the included species 

 are of small size, with the disk up to 5 mm. in diameter ; the arms are 

 6 or 7 in number, from 3.25 to 5 times as long as the diameter of the 

 disk ; the disk is finely plated, shows very small and widely separated 

 radial shields, and bears numerous scattered stout spinules that are 

 from two to three times as long as thick, or even longer ; and the arm 

 spines are 4, subequal, or the uppermost the longest and the lowest 

 the shortest, becoming 3 at the arm tips. 



Genotype. — Ophiocomella caribbaea, n. sp. 



Included species. — Ophiocomella parva (H. L. Clark), O. caribbaea, 

 n. sp., and 0. schmhti, n. sp. 



Range. — Known from Mer Island, Torres Strait, Clipperton Island, 

 the Galapagos Islands, and the West Indies. Littoral. 



Affinities. — The genus Ophiocomella appears to be closely related 

 to that section of the genus Ophiocoma including 0. pnmila from the 

 Caribbean Sea and tropical west Africa, 0. alexandri from the west 



