Boone, Echinodermata, Cruises of "Eagle" and "Ara," 1921-28 83 



closely crowded together that in undisturbed parts of the surface, the 

 covering of granules appears continuous, concealing the individual 

 contours of the plates, except for the faint impression of delineation. 

 The marginal plates are similarly covered with these granules so 

 that the entire dorsal surface has a remarkably uniform covering. 

 The madreporite is small, unequally hexagonal, the dorsal surface 

 flattish, traversed by fine, irregular radiating lines. The superomar- 

 ginal plates are very prominent, similar to the inferomarginal plates 

 from which they are separated by a linear marking. There are four- 

 teen superomarginal plates on each ray, in addition to the small, 

 rounded, subconical terminal plate at the tip of each ray. The distal 

 three of the fourteen plates are smaller, wider than long, while the 

 intermediate eight plates are larger, squarish. There are fifteen 

 inferomarginal plates, the median seven being about opposite those 

 of the upper series, while the distal four of inferomarginals are more 

 crowded than the related distal three superomarginals. The infero- 

 marginal plates have their actinal margin convex. The actinal inter- 

 radial surface is covered with plates, those nearest the inferomarginal 

 plates being the smallest, frequently hexagonal; while from the 

 approximate third row from the inferomarginal to the center, the 

 plates are much larger, rhombic, closely packed together, and are cov- 

 ered with rounded, coarse, spaced granules, which are distinctly 

 larger than those covering the marginal plates. The adambulacral 

 plates are similar to the actinal plates, but larger, numerous and very 

 crowded together. Each plate bears a furrow of three, four to five 

 coarse, blunt, four-sided club-like spines, closely packed together and 

 laterally compressed. Outside of these is a second row, usually of 

 three similar but slightly shorter spines, followed by a third row of 

 three similar but shorter, squarish spines, beyond which there are 

 eight to nine coarse, blunt granules, larger than those of the actinal 

 plates, and forming two approximate rows. The furrow row spines 

 along the jaw angle are similar but a little longer and stronger than 

 the rest of the series. The papular pores occur singly and are quite 

 numerous, occupying large radial areas and extending nearly to the 

 center of the disk. A thorough microscopic examination of the speci- 

 men revealed no pedicellariae. 



References : Peltaster planus Verrill, Amer. Journ. Sci., vol. XLIX, 

 p. 135, 1885; Trans. Conn. Acad. Arts and Sci., vol. X, p. 170, 

 pi. 28, figs. 3, 3a, August, 1899. 



