70 



CYATHOCRINUS BRITTSI, n. Sp. 



Plalv IV, Fig. 35, basal view; Fig. 3G, azygous side view of the 



calyx. 



Species medium size. Calyx rather more than twice as wide 

 as high, and somewhat obpyramidal in shape, in the superior 

 part, though round over the subradial region. Sutures dis- 

 tinct, surface granular. Column large and round. 



Basals form a pentagonal disc, one-third wider than the 

 diameter of the column, which has a concave depression, 

 though shallow, for the attachment of the column. Subradials 

 slightly wider than high, the one on the azygous side being 

 much larger than either of the others, though extending but 

 little higher. First radials a little wider than high, longitudi- 

 nally convex, most convex in the superior part, which gives 

 the calyx, when seen from above, a subpentagonal outline 

 The upper part of these plates, too, is very thick, and the 

 facets for the articulation of the second plates are correspond- 

 ingly deep, and scarred very slightly, for the ambulacral canal. 

 The facets are about three-fourths of the width of the plates, 

 and have a slight transverse depression that indicates a gap- 

 ing suture. The first azygous plate broadly truncates a sub- 

 radial at about the middle of the first radials. 



This species will be distinguished, by its general form, from 

 all others, so that no comparison with any of them is neces- 

 sary for its identification. 



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

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

 cific name is in honor of Dr. J. H. Britts, one of the leading 

 naturalists of Missouri. 



Family PLATYCRINID^. 



PLATYCRINUS TUGURIUM, n. Sp. 



Plaie IV, Fig. 17 ', basal view; Fig. 18, azygous side view; Fig. 



19, summit view. 

 This species is above medium size, and belongs rather to the 

 discoid than to the bowl -shaped forms, and receives its specific 

 name from a fanciful resemblance to a hut. Calyx shallow; 

 pentagonal, two and a half times as wide as high. Plates 

 thick, sculptured. Sutures beveled. The surface is ornamented 



