43 



Species very large. Calyx round, bowl-shaped and broadly trun- 

 cated below, evidently for a very large column. Columnar canal very 

 large and round. 



Basal plates almost equal in size, though one of them is quad- 

 rangular, which shows that we have a Platycrinus before us. The 

 basal plates form an expanded basin with a broad, flat bottom. It is 

 nearly three times as wide as high, and the flat bottom for the attach- 

 ment of the column is nearly three fourths as wide as the top. It is 

 constricted so as to form a basal rim which is nodose or notched. 

 There are rounded nodes on either side of each suture, from the base 

 to the top, and a few rounded nodes on other parts of the plates. 

 Otherwise, the surface of the plates is finely granular. The orna- 

 mented basal rim would seem to be a support to the base of the 

 calyx, but the upper part of the basal plates is thin for so large a 

 species. 



Found in the Burlington Group, near Sharon, in southwestern 

 Missouri, by R. A. Blair, and now in the collection of S. A. Miller. 



PLATYCRINUS BR1DGERENSIS, n. Sp, 



Plate III, Fig. 8, azygous view. 



Species rather below medium size, and belonging to the pentag- 

 onal, bowl-shaped forms. Sutures not beveled. Surface finely gran- 

 ular. Plates thick. Column small and round. 



Basals form a low cup two and a half times as wide as high and 

 constricted above the base so as to form a basal rim. 



Articulating facets for the second radials occupy one-third the 

 width of the plates. Second radials very short, axillary, and bear 

 upon each upper sloping side two secondary radials, the last being 

 axillary, and bearing Upon one side, a free arm, while the other arm 

 bifurcates on the second plate, which gives six arms to each ray. 

 There are, therefore, thirty arms in this species. The arms are 

 slender and composed of alternating cuneiform plates, having very 

 fine pinnules. 



Found by Earl Douglass, on Bridger Mountain, near Bozeman, 

 Montana, and now in the collection of S. A. Miller. 



