PLATE XVl. 



MiCHELINA (PlETIRODICTYUM) MAXIMA. 



Calamopura maxima Troost. Geological Report of Tennessee, page 73. 1840. 

 ? CalamopoiamammiUuiin Castelnau. Terr. Silur. de I'Amer. du Nord., pi. 19, f. 3. 1843. 

 ? Favosites maxima Troost : in Owen's Rep. on Geol. Iowa, Wisconsin and Illinois. 



" " Yandell-Shumard. Contrib. Geol. Kentuck3'. page 7. 1847. 



" mammillnris Edw. -Haime. Polyp. Fossiles des Terrains Palajozoiques, page ^41. 



Fig. 1. A portion o£ a larger liemispheric mass, presenting the usual characters of the species. 

 The diaphragms are often mammillary or pustulose on their upper surface, as shown 

 in this figure. 



Fig. 2. A fragment showing numerous small cells alternating with larger ones. 



Fig. 3. An enlargement of the cells from the upper surface of a specimen, showing partial and 

 complete diaphragms with pustulose surfaces. 



Fig. 4. A longitudinal section of a solid mass, showing the minute pores in the walls of the cells. 



Fig. 5. An enlargement of several of the solid columns, to show the longitudinal striae and minute 

 pores. 



Fig. 6. A longitudinal section of a portion of a solid mass enlarged, showing interrupted and con- 

 tinuous diaphragms. 



Fig. 7. A section of a solid mass, showing the crowded complete and partial diaplnagms, and 

 exhibiting the pores in some of the cell walls. 



