134 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



form tooth. IVpically no actinal podicellarisp; ex(;cptionally these may be present 

 in northern examples. 



Description.— Xbiictnuil surface weak, paved ^\-ith fairly large, strongly stellate, 

 rather loosely joined plates, interspersed irregularly ^\ith fewer smaller-lobed or 

 entire, irregular secondary plates. Beyond about the basal third of ray the plates 

 lose the lobes, become rapidly smaller and roundish or irregular, and, where there 

 are no papulw, closer together. The large plates of the disk and basal part of ray 

 have five to nine unequal lobes, the secondary plates three to five or none. Papulaj 

 numerous and large, distributed all over disk (except a very narrow interradial 

 area near margin) and on ray to about two-thirds of R. Beyond about one-third 

 R the papulffi are confined to the sides of the abactinal area, the medioradial region 

 being free from them. 



Each primary abactinal plate is raised into a low circular tabulum, bearing 

 on its center a very long, slender, sharp, movable spine, the longest being 8 to 1 1 mm. 

 in length (or about one-half to two-thirds width of ray at base). Each large spine 

 is surrounded, on edge of tabulum, by a circle of eight to fifteen straight, very slender, 

 unequal, divergent, seta-like spinules, about one-tliird to over one-half the length of 

 spine. The small plates bear a group of divergent spmules only. In typical speci- 

 mens the whole surface of tlisk ami proximal third of ray is a mass of extraordinarily 

 slender spinules, the primary spines rising above the more delicate armament. 

 Beyond the region of abundant papulae (basal third), on ray the primary spines 

 rajiidly become fewer and smaller, and the secondary spinules also dimmish in 

 number and size, wliile the secondaiy plates have a few short, very dehcate spinelets. 

 Beyond, about the middle of my, all plates are armed with three or four of these 

 short delicate spinelets, forming a uniform nap. A few pectinate pedicellariije, 

 with two opposing combs of four to ten slender sharp spinelets, are scattered here 

 and there over the papular area. 



Marginal plates of two series alternate on proximal part of ray, but farther 

 along they are less evidently so. Plates of both series rather thin, longer than 

 wide, and with central spiniferous prominence. Superomarginals numerous (upward 

 to eighty-five), confined to side of ray on proxinial part, but encroaching more 

 farther along. Typically each plate bears two or three long, slender, movable, 

 briistling, pointed spines in a vertical series, surrounded by a circle of seven to twelve 

 auxiliaiy spinules of very variable length and robustness. In addition there are a 

 few nunute scattered thornlcts. There are from two to five odd interradial supero- 

 marginals, specimens from the same station varying in this respect. One of the 

 first superomarginals of an interradius grows at the expense of its neighbor, which 

 is crowded out of place. Sometimes it is difficult to determine whether such a plate 

 is prominent enough to be considered "odd." Usually about three or four inter- 

 radii have the odd plate (bearing usually one large spine, a smaller companion, 

 and several spuielots). The interradial plates, whether single or double, project 

 above the tops of the others. The supcromarginal spines are longer and stouter 

 than the abactinal ones. 



Inferomarginals larger than superomarginals, and like tliem very convex, the 

 prominence bearing a bristling group of two or three long spines (sunilar to but 

 sUghtly shorter than those of superomarginals) surrounded by about ten unequal 



