PLATE XXVII 

 PLEURODICTYUM LENTICULARE Hall (Pages 422-425) 



FiGUUK 1. — Lower side of initial cell, or nepionic stage, x -U- 



Figure 2. — Lower side of initial cell with one bud; first neanic 

 stage. X 3^. 



Figure -i. — Initial cell with two buds ; second neanic stage. X '^^■ 



FiGuiiE 4. — Initial cell with three buds; third neanic stage. X '^■ 



Figure 5. — Initial cell with four buds; fourth neanic stage, x '^. 



Figure 6. — Completed neanic stage; showing initial corallite (1) 

 and seven peripheral corallites (2-8). X '3^- 



Figure 7. — Interior of nepionic corallite. X 3J. 



Figure 8. — Exterior of same specimen. X '^• 



Figure 9. — Upper side of specimen representing first neanic or 

 Aulopora stage; consisting of nepionic cell and one bud. Apex of bud 

 opens into visceral cavity of parent cell. X 3^- 



Figure 10. — Profile of same; showing oblique apertures of corallites, 

 and thickened margin of parent cell. X 3^. 



Figure 1L — Lower side of preceding. X 3|. 



Figure 12. — Upper side of completed neanic stage; showing incep- 

 tion of eighth cell. X 3^. 



Figures 1-6 are taken from epithecal lines of growth shown in Plate 

 XXVIII, figure 2. Remaining figures are from actual specimens. 

 Numbers refer to order of calical succession. 



Lower Ilelderberg CJroup, Albany county, New York. 



