41 



raclinls. and cnlirrly wifhiii tlu' basal coiu-avity. First j)rimary 

 radials ]>yraniiiial. liejitagoiial and licxa^oual. Second primary 

 radials about one-third as lart;C as thr first, nearly as long' as wider 

 peiita.L;onal. Third ])rimary radials abnnt tlic size of the second, hex- 

 agonal, and suppiirt on each of two injper sides the sei^ondary radials. 

 Our s])ecinien is sligiitly injured at the l)ase of the arms, but iis near 

 as can be determined there are three secondary radials in each si^rieB, 

 the last being a.xillarv and supporlinu' the arms. This gives twentj'^ 

 arms to the si)ecii's. The arms are (-(unposed of a single .series, of 

 cuneiform |)lates. each one of which l)ears a long, strong pinnule. ' 



Jn the regular interradial area, sliown in the illustration, tlie first 

 plate is as large as a first primary radial, truncatcsa sul)radial. and is 

 followed by two somewhat smaller plates in tlie second range, two quite 

 small plates in the tliird range, and one or more in the fourth range, 

 xVbove the fourth range the plates are not accurately determined. 

 This is evidently a regular interradial area. The other areas and the 

 vault are unknown. 



This species will be readily distinguished from B. (loinjhu^si hy.^ 

 being a smaller species, having only twenty arms instead of thirty 

 or more, and by the single series of arm plates instead of a double 

 series. 



Found by Earl Douglass in 1 he I ppei- l>urlington or Lower Keokuk 

 (iroup. (Ml I'lridger ^Jimntains. near Bozeman. Montana, and now in 

 liis collection. • s 



UHODOt'KIXrS liKIOCIiUENSlS, U. sp. 



Plate III. Ji;/. •>, >ti<lr ricw. 



Species below medium size. C'aly.x gloljular or subspheroidal. No 

 radial ridges. Plates gi'anular. not sculi)tured. Basal cavity moder- 

 ately deep, column verj- large. comjKised of very short pieces. This 

 species has twenty arms. The arms are small. 



This s^Decies is distinguisheil by the gloljular calyx, large columii 

 and small arms. 



Found in the IJui-lington or Keokuk (ii-oup l)y Karl Douglass, in 

 Bridger Mountains. Montana, and now in his collection. 



