WEST INDIAN STAEFISHES 



69 



Superomarginal plates well developed, larger than dorsals, 

 naked, or with few spaced submarginal spinules. 



Inferomarginal plates are about as large as the upper ones, 

 more prominent and form the thin margin ; their outer edge has 

 a comb of slender spines ; their upper surface has a second par- 

 allel row of small spines, no papulae pores between the rows. 



Interactinal plates are imbricated in regular chevrons, each of 

 which, except the first, has an impaired median plate. Most of 

 these plates have two or three spinules standing side by side, 

 otherwise the plates are naked. 



Adambulacral plates have a horizontal regular inner comb of 

 about three small spines discontinuous with the spines on the 

 actinal face, which stand in a transverse line, usually of two 

 or three. This genus resembles Asterina and Asterinides pretty 

 closely, not only in appearance, but also in the arrangement of 

 the imbricated dorsal plates and their spinules, and the position 

 of the papulae. The plates are larger, however, and do not be- 

 come so numerous and small toward the margins. The mar- 

 ginal plates are much larger, and thicker, and therefore the 

 margin is not so thin and acute. 



The interactinal plates and their spinules are much as in As- 

 terina, though larger and much fewer. The presence of a regular 

 furrow-comb of adambulacral spines is another similar feature, 

 though the spines on the actinal face stand in a transverse row, 

 not as they do in Asterina. 



This genus, therefore, is a sort of connecting link between 

 Asterinidae and Poraniidae. Its affinities seem, on the whole, to 

 be more with the latter, though the thick dermis found in most 

 genera of the latter is lacking. The genus most nearly related 

 is, perhaps, Lasiaster'^^ of Sladen, if this be distinct from the 

 earlier genus Rhegaster Sladen, which is denied by some. 



15 Lasiaster Sladen, op. cit., p. 371, 1889. All tlie plates, above and 

 below, and both marginals covered with thick dermis and all have a compact 

 cluster of numerous small spinules, but they are absent from the sutural 

 lines. Superomarginal plates are rather large and their outlines are visible 

 through the dermis. Infer omarginals not larger, but more prominent, finely 

 spinulated on both sides and with a row of spinules on the outer end. 



Adambulacrals have two furrow spines, nearly or quite side by side prox- 

 imally and becoming oblique distally; actinal face has three spines in a 



