URANASTER KINAHANI. 105 



differentiated in the disc and proximal regions of the arms. There is no visible 

 odontophor, but there are well-developed ventrolateralia which fill out the inter- 

 radial regions and cause the interbrachial arcs to be large and well rounded. 

 Madreporite apical. 



Genus URANASTER, Gregory. 

 1899. Uranaster, Gregory, Geol. Mag., dec. iv., vol. vi, p. 348. 



Generic Characters. — Disc comparatively small, arms long. 

 Genotype, U. Hnaliani (Baily), which is closely akin to the form described by 

 Schuchert (85, p. 142) as Petraster speciosiis. Miller and Dyer. 



1. Uranaster kinahani (Baily). Plate V, figs. 1 — 5 ; Text-figs. 60 — 63. 



1878. Palasterina kinahani, Baily, iu Kinahan, Man. Geol. Ireland, pp. xv, 26, pi. 2, fig. 1. 



1879. „ „ Baily, Mem. Geol. Surv. Ireland, Expl. Sheets 169, 170, 180, 181, pp. 58, 



59, g. 6. 

 1899. Uranaster kinahani, Gregory, Geol. Mag., dec. iv, vol. vi, p. 348. 

 1910. ,, ,, Schondorf, Jahrb. nassauiscli. Ver. Naturk., vol. Ixiii, p. 225. 



1914. ,, ,, Schucliert, Fossilium Catalogus, Aniraalia, pt. 3, pp. 7, 43. 



1915. „ „ Schuchert, Bull. 88, U.S. Nat. Mus., p. 155. 



Material. — Imprints of portions of four individuals in the British Museum 

 (Nat. Hist.) (nos. E. 194, E. 13110) were regarded by Gregory as the topotypes 

 of the species. There are also five specimens in the collection of the Geological 

 Survey of Ireland (nos. S. 1443, S. 1439a, S. 14396, S. 1441 and S. 144P, the last 

 of these being an imprint of the specimen figured by Baily). 



Apical Surface (PL V, figs. 2, 4 ; Text-figs. 60, 61). — The apical surface of 

 the disc and arms is bounded not by supero-marginalia but by infero-marginalia. 

 These are small and globular at the extremities of the rays (PI. V. fig. 4) but soon 

 become straight-sided and closely fitting, thus affording firm support to the body. 

 As seen in apical view they always appear longer than broad. An oral view of the 

 form shows, however, that in the interradii their breadth is really greater than 

 their length (Text-fig. 63). Their surface, either in apical or oral view, is almost 

 flat. There are no articulations for prominent spines as in Petraster speciosus. 

 The apical plates inside the infero-marginalia differ considerably in arrangement 

 in the various portions of the arm. Plates analogous to the supero-marginalia 

 of the Promopalgeasteridge maybe recognised in the proximal region (Text-fig. 60). 

 They are highly convex with a rounded base which at times may be stellate. 

 Similar plates are found in P. speciosus, where " at the apex of the rays the 

 supramarginals are highly convex and nearly circular in outline but soon pass into 



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