146 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



PETRASTER (?) AMERICANTJS (D'Orbigny). 

 Plate 26, fig. 2. 



Asterias GRAHAM, ANTHONY, and JAMES, Amer. Journ. Sci., eer. 2, vol. 1, 1846, 



p. 441, figure but no description. 

 Ccelaster americanus D'ORBIGNY, Prodr. de Paleont., vol. 1, 1849, p. 22 (name 



proposed). 

 Asterias anikonii DANA, Manual Geol., ed. 1, 1863, p. 221, with figure but no 



description. 

 Palasterina (tyjamesi DANA, Amer. Journ. Sci., ser. 2, vol. 35, 1863, p. 295; Manual 



Geol., ed. 2, 1864, p. 221, with figure but no description. 

 Palseaster jamesi HALL, Twentieth Rep. N. Y. State Cab. Nat. Hist., 1868, p. 286; 



rev. ed., 1868=1870, p. 329. MEEK, Geol. Surv. Ohio, Pal., vol. 1, 1873, 



p. 62, pi. 4, fig. 4. 



Meek's description. " Through the kindness of Mr. U. P. James, 

 of Cincinnati, the discoverer of this fossil, I have now before me the 

 original typical specimen, which I found not in a condition to be 

 fully and systematically characterized, nor perhaps to afford the 

 means of determining, beyond doubt, its generic affinities. It 

 evidently attained a large size, and has a comparatively large disk, 

 with its five rays rather broad at their inner ends, somewhat rapidly 

 tapering, and apparently longer than the diameter of the disk. It 

 evidently lies [does lie] in the matrix in such a manner as to show the 

 ventral side [the inner dorsal aspect of the ventral plates], but pre- 

 sents the appearance of having the marginal and disk plates of this 

 side removed [they are present]. The five pairs of oral pieces [proxi- 

 mal adambulacral plates] are seen in place, and proceeding outward 

 from these can be seen a row of adambulacral pieces on each side 

 of each of the rather wide [narrow] ambulacral furrows. These 

 latter pieces are [proximally] nearly three times as long as their 

 diameters in the direction of the length of the rays, and quite promi- 

 nent at their inner ends, where they are articulated together by little 

 processes and corresponding sockets or sinuses; while the outer 

 two-thirds of each is flattened and distinctly more depressed than 

 their inner ends. Outside of, and alternating with, the outer flat- 

 tened ends of these adambulacral pieces, a row of [inframarginal] 

 nearly square, or more or less oblong pieces, may be seen all along the 

 margins of the rays, and connecting at their axilla in such a manner 

 as to leave room for several disk [or interbrachial] plates between 

 them and the oral and inner adambulacral pieces." 



In each interbrachial area there are inserted between the infra- 

 marginals and adambulacrals interbrachial plates as follows: Proxi- 

 mally one hexagonal plate upon which rest two similar plates mar- 

 gined by the inframarginals. 



"At some places within the [narrow] ambulacral furrows, remains 

 of ambulacral ossicula can be seen deeply interlocking with the 

 inner ends of the adambulacral pieces, but their exact form, and the 



