PLATE XVI 



Page 



Figs. 1 to 10. Pbasopora simulathix Ulr 24i 



1 and 6. Vertical and tangential sections, xi8, of a specimen of the var. orientalis from 



Trenton Falls, N. Y. 



2 and 7. Similar sections of a Canadian (Ottawa) example of the same variety. 



3 and 8. Similar sections of a Kentucky specimen of the western or typical form of the 



species. 



4 and 9. Vertical and tangential sections of a specimen from the lower part of the Galena 



limestone at Mantorville, Minn. Mus. Eeg. No. 5986. 



5 and 10. Similar sections of another example of the typical form of the species from the 



upper third of the Trenton shales at St. Paul. 



Figs. 11 to 15. Pbasopoba conoidea Ulr 24! 



11 to 13. Lateral, basal, and one sectional view of three specimens of this species, natural 

 size. 



14. Tangential section xi8, showing the thin walls and minute acanthopores which are 



characteristic of the species. 



15. Vertical section, xi8. The abundant tabulation of the tubes is the chief peculiarity 



broughtout by this kind of section . 

 Upper third of the Trenton shales near Cannon Falls, Minn. 



Figs 16 and 17. Pkasopoba sblwtni Nicholson 25( 



16. Vertical section x]8, showing the isolation and semi-circular form of the cystiphragms. 



17. Transverse section of S3,me x 18. 



Upper part of the Galena shales near Cannon Falls, Minn. 



Figs. 18 and 19. Pbasopoba insttlaris, var . fillmoeensts, n . var. . , 25S 



18. A tangential section xi8, showing the different appearance of the inter-zooecial spaces 



when compared with typical P. insularis. 



19. Small portion of a vertical section xi8, showing the vesicular character of the inter- 



spaces to which is due the difference referred to in the preceding paragraph. 

 Probably from the'Trenton shales near Fountain, Minn. 



Figs. 20 to 23. Pbasopoba insulaeis, n. sp 251 



20. Tangential section of an excellently preserved specimen, xi8. 



21. Small portion of same X50to show the minutely cellulose character of the walls. 



22. One zooecial tube with adjacent mesopores and one wall with adjoining cystiphragms 



and diaphragms, xi8. In showing the much greater abundance of the cystiphragms 

 and diaphragms when compared with other species of the genus, this figure, though 

 small, is suflflcient for the identification of the present species. 



23. Small portion of another tangential section, x]8, in which the zocecial tubes are more 



frequently in contact than in fig. 20. 

 Galena shales near Cannon Falls, Minn. 



Figs. 24 to 26. Pbasopora contigtja Ulr 24J 



24 and 25. Vertical and tangential sections, xi8, of a specimen from the upper part of the 



Trenton shales of Goodhue county, Minn. 

 26. One zooecium and adjoining' mesopores of same x35. Mus. Eeg. No. 5989. 



