PLATE XXlV. 



Fig. 1 to 4. Hbmiphbagma ottawense (Foord) 30 



1 and 2. Two portions of a tangential section xi8, stiowing differences due to age. 



3. Vertical section X9. 



4. Small portion of the peripheral region of the same X35. 



Upper part of the Galena shales, Mantorville, Minn. Survey Museum, Keg. No. 6002. 



Figs. 5 to 19. Hbmiphbagma ikbasum Ulr ; 29 



5. Vertical section xg. 



6. 7, 9 and 14. Four tangential sections xi8, exhibiting individual variations. 

 8. Small part of a transverse section xi8. 



10 to 13. The surfaces of four specimens x9, flg. 10 representing a good average, fig. 12 the 

 appearance of young examples, and figs. 11 and 13 the fully matured conditions. 



15 to 19. A group of five specimens, three of them of the average size, vyhile 17 is the largest 

 and 18 one of the smallest seen. 

 Lower third of the Trenton shales at Minneapolis, and the Galena shales near Cannon 

 Falls, Minn. 



Figs. 20 to 23. Hemiphbagma tenuimubale, n. sp 30: 



20. Vertical section xi8. 



21 and 22'. Tangential sections x]8, the first showing the fully matured condition, the 

 second a younger stage in the development of the zoarium. 



23. Surface of a well preserved example showing the incomplete diaphragms in the zoceclal 



cavities, xg. 

 Galena shales near Cannon Falls. 



Figs. 24 to 31. Stbomatotbypa ovata, n. sp 30i 



24. Surface of an old example xg. 



25. Well preserved specimen consisting of several layers, natural size. 



26. Small portion of one of the first layers of same xi8, showing an aged condition. 



27. Part of the last layer of same xi8, showing appearance of surface in the youngest stage 



observed. 

 28 and 29. Tangential and vertical sections xi8, of an example consisting of three distinct 



layers of zocecia 

 30 and 31. Another pair of sections, vertical and tangential, the latter illustrating a more 



aged condition than is shown in flg. 28; xi8. 

 Middle third of the TrentOn shales, St. Paul and Minneapolis. 



