PLATE IV, 



Page 



E'igs. 1 to 7. Phtllopobina stjblaxa, Ulr 20! 



1. and 2. Reverse side of small fragment, natural size and portion of same X9, showing 

 striated character of this side in young or exfoliated examples. Lower Trenton lime- 

 stone, Minneapolis, Minn. Survey Museum. Reg. No. 5954. 

 3 and 4. Another fragment from the same locality, exposing the obverse side, natural size, 

 and portion of same xg. 



5. Tangential section, xi8, showing appearance of zocecia at varying depths. 



6. Two transverse sections of branches, xis. \ 



7. A rather loosely woven frond from the "Glade" limestone at Lavergne, Tenn.; natural size. 



Figs. 8 to 14. PHTLLOPOErSTA BETICULATA (Hall) 21( 



8. A frond exposing the reverse side, natural size, Minneapolis, Minn. 



9. Portion of same, xg. 



10 and 11. Another fragment from the same locality, natural size and xg. 

 12. Small fragment, liliewise from Minneapolis, exposing the obverse face, xi8. 

 13 and 14. Obverse and reverse sides of two fragments obtained from washings of Galena 

 shale at Cannon Falls, Minn.; xi8. 



15. Tangential section, xi8, of an example from Trenton Falls, N. Y. 



Figs. 16 to 21. Phtllopokina halli Ulr 21: 



16. Reverse side of a specimen, natural size, showing irregular arrangement of fenestrules. 



17. Celluliferous side of another fragment, natural size, showing the irregular solid swellings. 



18. Surface of same, xg.. 



19. Reverse side of same, xg. 



20. Tangential section, xi8, cutting the zocecia just beneath- their mouths. 



21. Another portion of same section, xi8, where It divides the zoarium at a deeper level. 

 Upper third of the Trenton shales at St. Paul, Minn. 



