sti-iction below the articulating facet, and by the semi-elliijtical 

 facet. These surface characters readily distiuo-uish it fi-om 

 other species. 



Pound by R. A. Blair, in the Burlington Group, at Sedalia, 

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



PLATYCKINUS CASULA, n. Sp. 



Plate /r, Fig. 37, basal view; Fig. 38, az/jgoiis side on the right; 

 Fig. 3!), view opposite the azygous side; Fig. 40, summit view. 



Species medium size and belongs to the bowl-shaped forms. 

 Calyx bowl-shaped, pentagonal, rather more than one and a 

 half times as wide as high. Plates thick. Sutui-cs broadly 

 beveled. Sui-face without ornamentation. Column round at 

 the calyx. 



Basal disc pentagonal, nearly three times as wide as the 

 diameter of the column and having a height about equal to 

 the thicknes.s of a plate. It is concave below for the column 

 attachment, and bordered by an angular pentagon from which 

 it is beveled to the suture above. First radials a little wider 

 than higli, slowly expand to form the cup and become convex 

 toward the facets, for the second radials. The facets are semi- 

 elliptical, directed at an angle of forty-five degrees, and occupy 

 about half the width of the plates. The second radials are 

 vei-y short and axillai-y. The uiubulaci-il notch is small in l:)otli 

 the first and second radials. The angles for the reception of 

 the interradials, which are in fact plates of the vault, are quite 

 obtuse. 



The vault is only slightly convex and is covered with a few 

 I'ather large convex ])lat(>s. Five large plates occupy tlu> central 

 part and these arc surrounded liy a single row of plates con- 

 sisting of the interradials and those covering the ambulaci'al 

 canals and tho.se forming the jjrobo.scis on the azygous side. 

 The proboscis is large and consists of numerous small plates, 

 and the first azygous int(>rradial, which is large, stands upright 

 aiul forms pari of it. 



The species is distinguished Ijy its jientagonal. bowl-shape, 

 absence of ornamentation and peculiar vault and proboscis. . 



Found by R. A. Blair in the Burlington Group, at Sedalia, 

 Missouri, and now in the collci-lion of S. A. Miller. 



