WEST INDIAN STARFISHES 



141 



spinelets in a rosette of two circles on the larger plates, about ten 

 to twelve in the inner circle and twenty to twenty-four or more 

 in the outer one, and many of the larger plates have an erect 

 central sharp spinelet, often more than twice as long as the di- 

 ameter of the plate. There is no central group of larger spines 

 on the disk, but some of the plates there are a little larger than 

 the average. 



The papular pores are in a small, median, specialized cluster 

 of five or six. A central larger pore is surrounded by four 

 plates, a little larger and more prominent than those adjacent, 

 and Tvith a rather larger central spinelet. The side of each plate 

 next the pore is angulated and bears a miniature comb of minute 

 spinules. Thus the four plates are convergent over the pore, 

 and appear to be movable, to some extent, like an operculum, for 

 in some cases they lie flat and conceal the pore and in other cases 

 they have the inner end raised, exposing it. Two of these plates 

 are in the median radial line; the others are between them, to 

 right and left.^^ Two or four smaller pores appear between the 

 outer angles of these four plates. No others are visible on some 

 of the rays ; on others an additional small pair appears more dis- 

 tally. The central dorsal pore is distinct. 



The superomarginal plates have a small acute spine; that on 

 the fourth plate is only slightly longer; some of the more prox- 

 imal plates have two spines, one above the other. 



The inferomarginal plates have one marginal spine, equal to 

 the upper ones, and also have a group of four to six or more sec- 

 ondary sharp spines, of unequal sizes, below their base, some of 

 them half as long as the marginals. These grade do^mward into 

 numerous sharp spinelets that closely cover the inferior surface, 

 the lower ones minute. 



The adambulacral plates have a prominent angulated inner 

 end and bear a series of about seven to nine very slender spines 

 on the edge. The actinal face usually has two elongated, very 

 slender, sharp, unequal, larger spines. Sometimes a fasciculated, 

 papilliform pedicellaria, with about four valves, replaces the two 

 spines on some of these plates. 



2* These appear to be the same as those spoken of by Perrier as four 

 plates forming a cross. 



