PLATE 34 A. 
pj fr< i_ 513. 3. Astrocerium pyriforme. ( P a g- 
1 a. A spheroidal form of this species. 
1 b. A turbinate form, the cells increasing rapidly from a narrow base. 
] c. An irregular turbinate form of larger size. 
1 d. A portion enlarged, showing the internal structure of the cells. 
1 e . An enlarged portion from the inner walls of the cells, showing the granulated or papillose surface from 
the bases of the spiniform rays. 
pjg. 2, 3. 514. 4. Astrocerium constrictum. (Pag- 123.) 
2 a. A fragment of a hemispheric mass, natural size. 
2 6. A portion of the same enlarged, showing the constricted growth at intervals. 
2 c. A transverse section of the same enlarged, showing the stellate character of the ends of the columns. 
3 a. A small hemispheric form of this species. 
3 6. The base of the same, showing its mode of growth upon the valve of an Atrypa. 
3 c. Profile view, showing the form and elevation. 
3 d. The base of a larger specimen, which commenced its growth upon a small shell. 
3 e. A portion of the surface enlarged, showing the form and apparent stellate character of the cells. 
