PLATE XV. 



Page 



Figs. 1 to 6. MONTICULIPOEA (?Prasopoka) gbandis Ulr 21' 



1. A small lobate mass of the natural size. 



2. rragment of a subramose example, natural size. 



3. Surface of same X9. 



4. Several zooecia of same, xiS, exposing the cystiphragms. 



5. Tangential section xi8. 



6. Three portions of a vertical section, xi8, showing extremes of variation in the tabula- 



tion of the zooecial tubes. Mus. Reg. No. 5969. 

 Base of the Trenton shales at Minneapolis. 



Figs. 7 and 8. Monticulipoea vp^ethbebti ?Ulrich 211 



Tangential and transverse sections, xi8, of a specimen from the Trenton limestone at 



Minneapolis. Mus. Reg. No. 596Y. 



Figs. 9 to 12. MONTICULIPOEA INCOMPTA, n. sp 21' 



9. Tangential section xi8. 



10. Small portion of same x50, showing the peculiar structure of the walls. 



11. Vertical section xig. 



12. One of the walls X50. 



Middle third of the Trenton shales, Minneapolis. Mus. Reg. No. 5968. 



Figs. 13 to 15. Atactopoeella insubta, n. sp i 22 



13. A crinoid column covered with the zoarium of this species, natural size. 



14. Tangential section xi8. 



15. Portion of same X50. (See also plate XVIII.) 



Middle third of the Trenton shales at Minneapolis. Mus. Reg. No. 5985. 

 Figs. 16 and 17. Atactopoeella ttpicalis, var. pe^cipta, n. var 22 



16. Vertical section X 18. 



17. Tangential section X50. (See also plate XVIII.) 



Middle third of the Trenton shales, Minneapolis. Mus. Reg. No. 5984. 



Figs. 18 to 21. Atactopoeella ceassa, n. sp 22 



18. Tangential section X 18. 



19. Small portion of same, x50, showing the structure immediately beneath the surface of a 



matured example. 



20. Another portion of same x50, showing the appearance at a deeper level in the zoarium. 



21. Vertical section, xi8. 



Galena shales near Cannon Falls, Minn. 



