EEVISION OF PALEOZOIC STELLEROIDEA. 155 



two pairs of marginal columns filled with small tuberculate plates 

 arranged in transverse rows. The other genera have the plates in 

 longitudinal columns. 



URANASTER KINAHANI (Baily). 



Palasterina kinahani Baily, in Kinahan, Man. Geol. Ireland, 1878, pp. xv, 26, 

 pi. 2, fig. 1; Mem. Geol. Surv. Ireland, Expl. Mem. Sheets Nos. 169, 170, 

 180, 181, 1879, pp. 58, 59, fig. 6. 



Uranaster kinahani Gregory, Geol. Mag., dec. 4, vol. 6, 1899, p. 348. — Schondorf, 

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



This species occurs abundantly as natural molds in the Caradoc 

 (Upper Ordovicic), near Ballymadder Point and Bannow, Wexford, 

 Ireland. A specimen is in the British ^luseum (Natural History), 

 No. E 194. 



URANASTER ELIZ^ Spencer. 



Uranaster elizse Spencer, Mon. Brit. Pal. Asterozoa, pt. 1 (Palseontogr. Soc. for 

 1913), 1914, pp. 18, 20, 23, figs. 18, 23. 



From the Ordovicic of Great Britain. 



Genus PAL.<^OSTELLA StUrtz. 



Palxostella Stijrtz, Palseontographica, vol. 36, 1890, p. 230, pi. 31, figs. 42, 43; 



Verb. natiirh.Ver. preuss. Rheinl.,etc., vol. 50, 1893, pp. 42, 58, pi. 1, figs.5-8, 

 Palsenedria Sturtz, Verb, naturb. Ver. preuss. Rbeinl., etc., vol. 50, 1893. 



p. 12 (genobolotype the second sj^ecimen of Palxostella solida). 



Description. — Animal attaining a large size, with large pentagonal 

 interbrachial arcs. Rays five, stout. Ambulacral grooves wdde and 

 apparently regularly tapering. 



Abactinally the inframarginals are also the marginals for this 

 area. Near the distal ends of the rays the supramarginals adjoin 

 and lie either partially over or inside of the inframarginals and 

 continue nearl}" to the axillse. There also seems to be a single radial 

 column, confined, however, to the distal third of the rays. Other- 

 wise the abactinal skeleton consists of very numerous, small, irregu- 

 larly shaped, loosely interlocking plates without definite arrangement. 



Madreporite abactinal. 



Actinally the animal is bounded by subquadrate, numerously 

 spine-bearing, inframarginal plates which increase rapidly in size 

 towards the axillae, where they are ponderous and nearl};- tAvice as 

 wide as long. Ambulacral plates alternating, L-shaped, with single 

 columns of podial openings. Adambulacrals subquadrate, prominent, 

 mcreasing regularly in width proximally and bearing spines like 

 the marginals. Interbrachial areas large, reaching to near the 

 distal ends of rays, widely separating the inframarginals from the 

 adambulacrals in the axiUary region, and the space occupied by 

 very numerous, small, spine-bearing, apparently irregularly dis- 

 posed plates. * 



