PLATE XXIX 

 PLEUROPICTYUM LENTICULARE Hall (Pages 423,424) 



Figure 1. — Outline of ealices of specimen Plate XXVIII, figure 2; 

 showing central primary cell and seven peripheral ealices numbered in 

 the order of their development. X 3-J. 



Figure 2. — The same ; side view. 



Lower Helderberg Group, Albany county, New York. 



