EXPLANATION OF PLATES. 



PLATE 50. PAGE 



HELIOPHYLLUM SULCATUM. 185 



FIG. 1 — Lateral view of a large corallum. 



FIG. 2 — Lateral view of a weathered specimen showing the ves- 

 icular structure. 



FIGS. 3-4 — Calix views of two different examples, showing the long 

 fossette. 



FIG. 5 — Lateral view of a specimen exhibiting the vesicular structure 

 and the deep cup. 



FIG. 6 — Calix view of another individual. 



