WEST INDIAN STARFISHES 45 



Catal. British Echinod., p. 95, 1892. Fisher, 1911&, p. 266. Verrill, op. 

 cit., p. 209, 1814o. 



Cribella Forbes, Brit. Starfishes, p. 100, 1841, or December, 1840. 



Echinaster (pars) Miiller and Trosehel, April, 1840; Syst. Aster., p. 22, 

 1842. 



Cribrella Liitken, Gronl. Echinod., p. 30, 1857. Norman, Ann, and Mag. Nat. 

 Hist., XV, p. 124, 1865. Verrill, Proc. Boston Soc. Nat. Hist., x, p. 345, 

 1866. Perrier, Eevis. Stell. Mus., Arch. Zool. Exper., iv, p. 373, 1875. 

 A. Agassiz, North Amer. Starfishes, p. 113, pi. xviii, 1877 (structure of 

 skeleton). Viguier, Squellette des Stell., Arch. Zool. Exper., vii, p. 126, 

 pi. vii, figs. 8-15, 1878 (odontophore). Sladen, Voy. Chall., xxx, p. 540, 

 1889. Perrier, Exp. Trav. et Talism., p. 143, 1894. Ludwig, Fauna 

 Arctica, p. 473, 



Stellate starfishes usually with, five terete, slender rays ; some- 

 times with short rays and wide disk. Sometimes with six or 

 more rays in autotomous species. 



Dorsal plates are numerous and small, united into a rather 

 closely reticulated structure, bearing numerous papular pores, 

 either isolated or in small groups. Dorsal spinules minute and 

 nearly uniform, crowded in divergent clusters on the convex 

 ossicles of the dorsal, lateral, and actinal surfaces. 



The madreporic plate is inconspicuous and usually spinulose ; 

 sometimes two are present in autotomous species. There is no 

 thick dermis over the plates. 



Supermarginals are small, often indistinct, and like the dor- 

 sals. Inferomarginal plates distinct, often larger than the su- 

 peromarginals, contingent with the latter distally, but often sep- 

 arated proximally by one, two, or more interpolated rows of 

 marginal ossicles, varying in number and extent, and thus caus- 

 ing great variations in the thickness and taper of the rays. In- 

 teractinals and inferomarginals similar and closely joined, con- 

 vex, and covered with small spinules; the rows are separated 

 by papular pores, which may also occur between the interactinal 

 and adambulacral plates. 



The two rows of marginal plates, the interactinal and the 

 adambulacrals agree nearly or quite in radial length, at least 

 proximally, so that they form regular transverse series. 



The adambulacral plates are transversely oblong. Their actinal 

 face is covered with numerous spinules in two or more transverse 

 rows, or in a compact group ; those near the furrow margin are 

 longer, and one to three may stand on the margin ; there is one 



