WEST INDIAN STARFISHES 



57 



Body usually rather flat, often thin, sometimes stellate with 

 long rounded rays; usually with five or six short rays, rarely 

 up to eight. Margins usually thin and formed mainly by the 

 inf eromarginals ; superomarginal plates small, usually scarcely 

 larger than the adjacent dorsals, generally with a comb or cluster 

 of spinules. Dorsal plates usually lobed or cross-shaped, flat 

 and more or less imbricated, sometimes not imbricated ; generally 

 covered with minute spinules, often in tufts or combs; some- 

 times covered with a soft, naked, or granular dermis. Ventral 

 side flat ; interactinal plates angular, flatish, imbricated or close- 

 ly united, usually covered with small combs or tufts of spinules, 

 sometimes vdth. only one; these plates form regular oblique 

 rows. Adambulacral spines simple, divergent ; generally in two 

 sets ; the furrow-spines form small, usually webbed combs of two 

 to eight. Those on the outer surface are in groups or fans, like 

 the interactinals, or single. Pedicellarise usually lacking ; when 

 present they are two-bladed, erect, forficiform. 



There is generally no single, dorsal, median, radial row of 

 plates; its place is taken by two, three or more alternating rows; 

 the larger of these plates have a papular pore or several pores 

 under the proximal edge. In some cases, especially while young, 

 there is a symmetrical median row of plates. These larger 

 plates usually show only one of the edges and part of one side ; 

 seen from the inside they appear much larger, often four-lobed, 

 and obliquely imbricated. The dorsal plates of the outer inter- 

 radial areas, in many species, have conical or pillar -like processes 

 extending downward and meeting similar uprising processes 

 from the outer interactinal plates, as stalactites meet stalagmites; 

 or they may not join directly, but be united by an intermediate 

 ossicle. In some genera they are differently joined. In typical 

 Asterina, and doubtless in many other genera, if not in all, the 

 genital pores are on the ventral side, in a pair, just outside the 

 jaw plates, but they are seldom visible in preserved specimens. 

 The madreporic plate is usually rather large and placed close to 

 the central area of the disk; sometimes there are two or more, 

 rarely five. 



The papular pores are dorsal and form several rows on the 

 median and lateral parts of the rays, and sometimes on adjacent 

 parts of the disk, but are absent from the more or less extended 



