40 



hears sevpii arms. Tlie axillnrv third secondary radial on tlio rij^lit 

 very clearly bears two arms and the axillary third secondary radial 

 adjoining the azygous area bears uix)ii one side an arm and u))on the 

 other two plates, the last one being axillary and supporting two arms. 

 It leaves, therefore, two arms to l)t' sn|)|)f)rted by the middle series of 

 ])lates. This arrangement may be peculiar to tliis ray. Tlie right 

 lateral ray is not fully exposed, as the sjjecimeu is on a shdi. but it 

 appears to jiave only six arms, but one appears to billnw the jilate 

 resting in the angle at the junction of the first secondary radials. 

 The species, therefore, possesses between thirty and thirty-five arms. 

 If the rays were uniform it would possess thirty-five arms, but 

 another specimen on tlie same slab shows one ray very clearly pos- 

 sessing only six arms. The arms are small and composed of a double 

 s(^ries of small interlocking plates that bi-ar strong pinnules. 



Ill the regular interradial area, shown, in the illustration, the 

 first i)lnte truncates a subradial, it is followed by two plates in tlir 

 second range, three in the third, and three in the fourth, above which 

 they are not disclosed. In the ay.ygous area the first ])late is twice 

 MS large as the first j)late in the regular ai-ea and truncates a very 

 large subradial. It is followed by four plates in the form of an arch 

 the middle one of which is as large as the first plate in a regular 

 area. There are also four plates, in the form of an arch, in the 

 third range, the middle one of which is the larger and above these 

 smalK'r plates graduate uj) into the vault. 



The vault is not exposed in either of our specimens. 



This is a strongly characterized species, 



Fo\ind by Earl Douglass, in whose honor we have projiosed thi> 

 specific name, in the U])per Burlington or Lower Keokuk (iroup. on 

 ISridger Mountains, near Bozeman, Montana, aiul now in his collec- 

 tion. 



RHODOCKIMS liOZICM.^NENSlS. n. Sp. 



PIdIc IITjJii/. i". side n'cic. 



Species rather below medium size. Calyx bowl-shaped, radial 

 ridges not defined. Plates sculptured and more or less pyramidal. 

 Basal cavity deep. Column medium size, round, and comiKiscd of 

 [ilates of equal length. 



Basals form a cone within the calyx, into which the end of the col- 

 umn is inserted. Subratlials not any larger than the first primary 



