252 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



of the plates of the innermost chevron, and other scattered plates, 

 have a pedicellaria with 2 slender, spatulate, denticulate, or entire 

 jaws, springing from a narrow base; and sometimes they have a 

 couple of pedicellarialike granules at one side, as in R. symhoUcus. 



Adambulacral plates at first with a nearly straight, then a slightly 

 curved furrow margin, but without an angular apophysis. On the 

 outer part of the ray this convexity is sufficient to separate consecutive 

 pairs of tube feet as the plates are placed exactly opposite. Furrow 

 spines at first 12, increasing to 14 or even 15, sharply four-sided, 

 compressed to an even thickness, truncate, very comblike, with a nearly 

 straight distal margin, but the 1 or 2 lateralmost are shorter. The 

 thickness of the spines is much less than their width (in the trans- 

 verse axis of plate). Separated from these by a slight space is a 

 curved series of 6 close-set heavy four-sided spines shorter than the 

 furrow spines and beveled from the base to tip, like a v\edge. Back 

 of these are 2 spaced rows of three- or four-sided prismatic granules, 5 

 or 6 to a row, these increasing to 3 rows on the outer part of ray. 

 Thus a plate may have 25 to 30 subambulacral granules, as the first 

 spinose series become& gradually reduced to granules. Manj'^ plates, 

 near their proximal end, have a stout pedicellaria composed of 3 

 or 4 incurved spiniform jaws modified from granules. In the type 

 these are not very numerous, and are lacking on the outer half of ray. 

 In specimens from station 5282 they occur on a majority of the 

 plates, and beyond the proximal third of the ray have 2 jaws, becom- 

 ing gradually transformed on the outer half of ray into the ordi- 

 nary pincer with narrow strap-shaped or slightly spatulate (variable) 

 jaws. These specimens also have the actinal intermediate pedicel- 

 lariae more numerous. 



Mouth plates with a straight furrow margin and 15 marginal 

 spines, the outer 10 truncate and four-sided, the inner 5 increasing 

 in size and becoming three-sided, compressed, and Imifelike. Parallel 

 to the furrow series are about 6 prismatic shorter, stouter spines 

 in line with the first subambulacral series, the outer part of plate 

 being occupied by 12 to 14 variable granules, in general like those of 

 the adambulacrals. 



Madeporic body very small, three- or four-sided, surrounded by 

 four plates, with a fifth encroaching, and situated about one-fifth r 

 from center. 



Anatomical noteH. — The gonads form a series of 5 small tufts 

 (probably more in the larger type), which begin at the middle of 

 the interradius and, following the fourth longitudinal series of abac- 

 tinal plates, just outside of the papular area, reaches to the third 

 superomarginal plate. This arrangement conforms with that found 

 in R. symholicus and R. nan/nus. The gonads resemble miniature 

 bunches of grapes, and each tuft lias a separate aperture. The 



