258 STUART WELTER 



is less satisfactory, but it seems to agree more closely with Pentag- 

 onaster than with any other, although the interradial arcs are some- 

 what deeper than is usual in that genus. In the recent species P. 

 arcuatus Sladen, 1 however, these arcs are nearly as deep as in the 

 fossil specimen, the proportion between the minor and major radii 

 being 1 to 1.93, while in the fossil specimen it is 1 to 2.08. 



The specimen also more or less closely resembles, in the char- 

 acters which are preserved, some of the recent species of Gnathaster, 

 a genus also belonging to the family Pentagonasieridae, in which 

 the interradial arcs are often much deeper than in Pentagonaster, 

 in G. elongatus Sladen, 2 the proportion of the minor to the major 

 radii being 1 to 3.5. This genus, however, is usually characterized 

 by the presence of an odd interradial marginal plate — a character 

 not clearly shown in the fossil specimen. In one of the interrays 

 such a plate seems to be present, but in the others not. For the 

 present, therefore, the specimen may be referred to the genus Pentag- 

 onaster. 



Pentagonaster browni n. sp. 



(Fig. 1) 



Description: Stellato-pentagonal in outline, major radius 24 mm , minor 

 radius n.5 mm . Disk large, apparently flat. Interradial arcs broadly rounded, 

 the rays elongate for the genus, rounded at their extremities. Marginal plates 

 large, about sixteen occupying each interradial arc from tip to tip of adjacent 

 rays, the character of their ornamentation not preserved. 



Horizon and locality: Fox Hills sandstone, S. E. \, Sec. 16, T. 32, R. 99, 

 near Lander, Wyo. 



Type specimen: Paleontological Collection, Walker Museum, No. 10725. 



1 Challenger Reports, Zoology. XXX, p. 277, Plate 52, Figs. 1, 2. 



2 Ibid., p. 288, Plate 48, Figs. 1, 2. 



