WEST INDIAN STARFISHES 89 



Form stellate, usually Tvith five slender, flexible rays, but the 

 number is variable in some autotomous species. 



Abactinal and marginal plates usually tesselated or subim- 

 bricated, in rows or irregular; in most cases granulose (covered 

 with rather thick, smooth skin in Leiaster), sometimes tuber- 

 culated, rarely spinose. 



Marginal plates are usually well developed, in two regular 

 rows, but often not conspicuous and rarely so thickened as to 

 form a rigid margin. They are similar to the dorsal plates, as 

 to granulation. 



Papulae usually numerous, mostly abactinal and lateral and 

 in groups, sometimes single; in some of the genera they occur 

 also between or below the marginals, or between the interactinal 

 plates. 



Adambulacral plates small, covered with either granules or 

 spinules, the margin bearing one or two rows of small spines, no 

 more. 



Pedicellariae often lacking; when present, usually bivalve, 

 sometimes spatulate and fossate. Superambulacral plates often 

 present. 



Genus Ophidiaster Agassiz (restricted). 



Ophidiaster (pars) L. Agassiz, Prod. Monog., 1834. Gray, op. eit,, 1840, 

 p. 283; Synopsis, 1866. Miill. and Trosch. (pars), Syst., p. 28, 1842. 



Ophidiaster (emended) Liitken, op. cit., p. 163, 1864. Perrier, Eevision, 

 p. 384, 1875; op. cit., 1884, p. 221 (descr.) 



Linckia (pars) Nardo, 1834. Von Martens, op. eit., p. 351, 1865. 



Disk small; rays slender, subterete, closely granulated. The 

 dorsal plates are in about three to five regular rows, leaving 

 squarish or angular papular areas between them in regular rows. 

 Papular areas sometimes occur, also, between the marginal rows ; 

 rarely, also, in one submarginal row. The marginal plates, which 

 form two regular rows, are not unlike the dorsals, and closely 

 'granulated. Interactinals are smaller, angular, and usually form 

 one or two narrow rows. Adambulacral plates usually have two 

 unequal small spines on the inner edge, and one just back of them 

 in the second series decidedly larger, stout, but not much elongat- 

 ed. Superambulacrals are usually present but small. Fossate 

 pedicellariae, usually with spatulate valves, occur on most species. 



