180 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



they remain beside tlie adambulacrals, become more and more 

 spinose, longer than wide, and eventually stellate in form and then 

 are inseparable from the abactinal plates. There are about 42 adam- 

 bulacrals in each column. 



TJ. pulchella is readily distinguished from Z7. ulricM and U. grandis 

 in being smaller, with more slender and graceful rays, and in its fewer 

 colunms of plates. From U. Tiuxleyi it is distinguished by the les3 

 convex rays and the far smaller number of plates. 



Cat. No. 60610, U.S.N.M. 



URASTERELLA GRANDIS (Meek). 

 Plate 27, figs. 6-8; plate 28, figs. 1, 2; plate 30, figs. 1-4. 



Stenaster grandis Meek, Amer. Joum. Sci., ser. 3, vol. 3, 1872, p. 258; Geol. Surv. 



Ohio, Pal., vol. 1, 1873, p. G6, pi. 3 bis, figs. 7a-7c. — ^Miller, N. Amer. Geol. 



Pal., 1889, p. 283, fig. 432. 

 Urasterella grandis Meek, Geol. Surv. Ohio, Pal., vol. 1, 1873, p. 67. 

 Palseaster harrisi Miller, Joum. Cincinnati Soc. Nat. Hist., vol. 2, 1879, p. 117, 



pi. 10, figs. 2, 2a. 



Original description. — "Attaining a very large size, with the body 

 or disk comparatively small, or only of the breadth of the united 

 inner ends of the five rays. Rays long, slender, gradually' tapering, 

 and very flexible, widest at their immediate connection Avith the 

 body, where they seem to be more or less depressed, but becoming 

 more nearly terete farther out. Dorsal side of body and arms com- 

 posed of numerous subtrigonal pieces that rise into pointed tubercles, 

 or sometimes assume almost the character of short spinules, and 

 are arranged in quincunx, so as to form about eight rows near the 

 middle of the rays; those of the outer two rows being a little larger 

 than the others. Dorsal pores apparently, rather large, and passing 

 through between the concave sides of contiguous pieces. Ventral 

 side of body unknown. That of the rays composed of the usual single 

 row of transverse adambulacral pieces on each side of the well 

 defined, rather deep, and moderately wide ambulacral furrows. 

 Adambulacral pieces rather more than twice as long as wide, ^nth 

 their longer diameters at right angles to the ambulacral furrows, 

 and rounding over from end to end so as to be most prominent in 

 the middle; while they do not connect with each other by flat sides, 

 but have httle projecting processes, and corresponding sinuses, 

 apparently for the purpose of impartmg greater flexibihty to the 

 rays." 



Emended description. — The largest specimen being doubled over 

 actinally does not permit of exact measurements, but it is, as near 

 as can be determined, as follows: R = 93 mm., r = 9 mm., E = 10.3r. 

 Another specimen spread flatly measures: R = 49 mm., 7*= 6.5 mm., 

 R = 7.6r. The smallest specimen (holotype of Palseaster hanisi) 



