PLATE XXX 



PLEURODICTYUM LENTICULARE Hall (Pages 423, 424) 



Figure 1. — Outline of upper side of specimen with eight peripheral 

 calices. X 3^. 



Figure 2. — Upper side of symmetrical specimen; showing general 

 features of calices, mural pores in central corallite, and thickened epithe- 

 cal border. X 3^. 



Lower Helderberg Group, Albany county, New York. 



