WEST INDIAN STARFISHES 109 



more or less closely correspondiDg vertically ; oblique in the type. 

 No odd interradial plate. 



The adambulacral plates bear a regular marginal row of three 

 to seven slender spinules, and usually two exterior longitudinal 

 groups or rows of shorter spinules, which may be angular and 

 obtuse, and toward the tips of the rays, some of them, in the type, 

 become larger and longer. Some of these spinules may be re- 

 placed by spinuliform or clavate, two or three-bladed pedicel- 

 lariae. 



The interactinal plates are angular, often rhombic, closely ar- 

 ranged in rows subparallel with the ambulacral grooves, cov- 

 ered with a rosette of granules, the central granules often re- 

 placed by a wide valvular pedicellaria. The dentary plates are 

 not very prominent. Small superambulacral plates are present 

 in all the species dissected. 



Mediaster (?) PEDiCELLAEis (Pcrrier) Verrill. 



Goniodiscus pedicellaris Perrier, op. cit., 1881ft, p. 23; Nouv. Arch, du Mus., 

 vi, p. 245, pi. iv, fig. 3, 1884. Sladen, op. cit., p. 756, 1889. 



Mediaster (?) pedicellaris Verrill, Revision Genera, p. 183, 1899. Fisher, 

 1911&, p. 197. 



One of the types of Perrier, in the Museum of Comp. Zoology, 

 examined by me, had the following characters: 



The radii are 18"^°^ and 59™™ ; ratio, 1 :3.3. Dorsal plates, large, 

 roundish, the summit convex when naked, but flat when cov- 

 ered with the spinules ; the largest have about sixteen marginal, 

 tapered, acute spinules, and one to five or more somewhat larger, 

 acute, central ones. Intervening papular pores large, single, 

 about six around each plate, except that there is none between 

 the plates in the median radial rows ; a row on each outer border 

 of the abactinal area extends nearly to the end of the rays, or to 

 within about ten marginal plates of the end. 



The median series of plates extends about four or five plates 

 farther than the lateral, but ceases within four or five plates of 

 the tip ; from thence the marginal plates are in contact. 



Superomarginal plates bevelled and covered with small, sharp, 

 spaced spinules; the upper spinules are shorter than the lower 

 ones, larger, stouter, acute, divergent; those around the margins 

 are similar and do not form regular fascioles. 



