PLATE XXY. 



Heliophyllum Halli. 



(See Plate :>3.) 



Fig. 1. Ve;tical section from near the outer surl;ace, greatly enlarged. 



Figs. 2, 5, 7. Fig. 7, represents a transverse section, natural size. Fig. 5, a portion of the same 

 enlarged. Fig. 2, a still further enlargement, showing the rays, the transverse ridges 

 and the interradial plates. 



Fig.*. H, G. Fig. 6 represents a transverse section with very closely arranged transverse dissepi- 

 ments. Fig. 3 an enlargement of another portion of the same specimen. 



Fig. 4. A further enlargement from the specimen Fig. 12, Plate 23, showing the thickening of the 

 rays and transverse dissepiments, and the more irregular form of the interradial 

 vesicles. This and fig. 1 are referred, with some doubt, to this species. 



Heliophyllum degener n. sp ? 



Figs. 8, 9. Two views of a specimen which is strongly contracted towards the upper part, and the 

 surface destitute of epitheca. 



Figs. 10, 11. Two views of a smaller specimen, showing a broader cup but similar surface. Hamil- 

 ton group, Skaneateles Lake, N. Y. 



Helioph^lll'm IIalli ? var. obconicum. 



Ficf. 12, 13. Views of the opposite sides of a specimen, showing tlie regular turbinate form and 

 distant lamellar ridges of the surface. Hamilton group, Skaneateles Lake, N. Y. 



