278 



NEW YORK STATE MUSEUM 



the cup formed of alternate narrow and wider rings. The basals 

 appear to be hexagonal and each is marked by two very prominent 

 keels running from the central portion of the plate toward the lower 

 angles. Both are bent, with the convex side toward the ring; at 

 their junction near the center of the plate they give rise to a short 

 vertical fold which soon divides into two less prominent keels or 



Fig. 4 Analysis of Lyrioc r in us? bee c her i. I nterradial plates 

 shaded and the position of the more prominent plate folds and ridges 

 indicated. 



ridges which pass outward to the radials ; between the former and 

 the latter are three faint folds, seen best next the edge of the plate 

 and perpendicular to this edge; there is also a strong transverse 

 ridge below and parallel with the truncate upper edge of the plate. 

 The pentagonal, completely separated radials carry very slightly 

 raised ridges continued from the basals; those near and parallel with 

 the lateral margins are the more prominent and extend vertically 



