154 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



PALASTERINA (?) RAMSEYENSIS Hicks. 



Palasterina ramseymsis Hicks, Quart. Journ. Geol. Soc. London, vol. 29, 1873, 

 p. 51, pi. 4, figs. 21-23.— Woodward, Geol. Mag., dec. 2, vol. 1, 1874, p. 96'. 



This starfish needs to be restudied in the light of modern knowl- 

 edge. The specimens represented by Hicks's figures 21 and 22 seem 

 to be referable to Petraster rather than to PalasteriTia, wliile that of 

 figm'e 23 appears to be nearer Mesopdlxaster. 



Formation and locality. — Said to be from the Tremadoc, but the 

 development of the stai-fish seems to be in harmony with Upper 

 Ordovicic time. The specimens are from Ramsey Island and St. 

 Davids, Wales, and are in Mr. Lightbody's collection. 



Genus URANASTER Gregory. 



Uranaster Gregory, Geol. Mag., dec. 4, vol. 6, 1899, p. 347.— Schondorf, Jahrb. 

 nassauisch. Ver. Naturk., Wiesbaden, vol. 63, 1910, p. 225. 



The name is "from Uranus, the grandfather of Pluto; the starfish 

 resembles the living genus PlutonasterJ' 



Generic description. — Animal deeply pentagonal, above medium size, 

 with well-developed interbrachial arches, and five long slender rays. 



Inframarginal plates marginal, large, and elongated in the direction 

 of the rays. These plates are apparently common to both the actinal 

 and abactinal areas. Abactinally adjoining the inframarginals is 

 another column of large submarginal plates ( ?supramarginals) 

 alternating with the former, and sometimes there are smaller acces- 

 sory pieces between these coliunns in the angles of the plates. The 

 rays have no medial or radial columns of prominent plates, but the 

 entire space bet\7een the submarginal columns is occupied by numer- 

 ous closely fitting, convex, or tubercular plates which are arranged 

 in alternate transverse rows, each having from three to four pieces 

 on each side of a ray. 



Interbrachial accessory plates numerous, polygonal, and, according 

 to Baily's figure of Z7. Mnahani, arranged in crescen tic rows conforming 

 to the shape of the disk margin. These plates do not appear to 

 extend between the marginals and adambulacrals beyond the mid- 

 length of the rays. 



Adambulacral plates tubercular, subquadrangular in outline, and 

 widest transversely in the medial tliird of the column. 



Ambulacral furrows very narrow, deep, and tapering gradually. 

 Ambulacral plates traversed by strong transverse ridges. 



Madreporite unknown. 



Genoholotype. — Palasterina Jcinahani Baily. Upper Ordovicic. A 

 second species is U. elizx Spencer, also from the Ordovicic of Great 

 Britain. 



Remarlcs. — Uranaster differs from Petraster, Palasterina, and 

 Lindstromaster in having the abactinal area of the rays between the 



