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There are, therefore, six arms in each of the three rays preserved, in 

 our specimen. The ray on each side of the azygous area is injured, 

 but, we think, from appearances, we can safely call this a thirty 

 armed species. After the arms become free they are composed of a 

 double series of interlocking plates. 



The first regular interradial is very large and it is followed by 

 either one or two small plates which are cut off from all connection 

 with the vault by the union of the tertiary radials above. The azy- 

 gous plates cannot be determined in our specimen. 



The vault is conical but smaller than the calyx and bears a long, 

 central proboscis, which is broken off at the top of the specimen 

 illustrated. 



This is a marked species, and. if we were to guess at the age of 

 the rocks from which it came, from an examination of the single 

 specimen, we would be inclined to say the Keokuk Group. But 

 some of the associated fossils figured and described, in this Bulletin 

 and Bulletin No. 10, have the aspect of Burlington fossils. Some of 

 the Government publications have called the rocks Carboniferous, 

 but no such fossils were ever found in the Carboniferous rocks in 

 any part of the world. When we described the forms in Bulletin No. 

 10. we had no hesitation in saying they came from the Subcarboni- 

 ferous and we can now be certain that they are from the lower half 

 of the Subcarboniferons. It is probable that all the fossils we have 

 examined are not from the same layers and some may belong to the 

 Burlington and others to the lower part of the Keokuk Group. 

 At present we are inclined to refer them to the Upper Burlington or 

 Lower Keokuk, because none of them are from rocks lower than the 

 Burlington or higher than the Keokuk, and we do not know whether 

 they are or are not from rocks of the same geological age. 



Found by Earl Douglass, in whose honor we have proposed the 

 specific name, on Bridger Mountains, near Bozeman, Montana, and 

 now in the collection of S. A. Miller. 



DOEYORINUS ST BOVIFORM1S, U. Sp. 



Plate IT, Fig. 7, azygous, side; Fig. 8, opposite view; Fig. 9, sum- 

 mit view. 



Species medium size, calyx and vault together subovate. Calyx 

 urn-shaped, narrowly rounded below. No radial ridges, but the 

 radial series project moderately at the arm bases, so as to notch the 

 circumference at the interradial spaces. Ambulacral openings 



