PLATE Vtl. 



Page. 



Figs. 1 to 5. Rhinidictya pediculata, n. sp • 13' 



I to 4. Four specimens of the natural size, showing the mode of growth prevailing in this 



species. Three of the specimens preserve the footstalk. 

 5. Surface of a slightly weathered example xg. In better preserved examples the nonpori- 

 ferous margins are much wider. (See description.) 

 Lower limestone of the Trenton formation, Minneapolis, Minn. 



Figs. 6 to 9. Ehinidictta tkbntonensis Ulr 13i 



6 to 8. Three fragments of the natural size. 



9. A well preserved fragment of the natural size and xg. (See also plate VI.) 

 Lower third of the Trenton shales, Minneapolis, Minn. 



Figs. 10 to 15 and 18 to 21. Ehinidictta mutabilis Ulr 12 



10. Surface of an old and excellently preserved fragment, x9- 



II to 14. Four representative specimens of the natural size. The original of flg. 11 belongs 



to the Sarvey Museum; Reg. No. 5g3g. It is from the upper third of the Trenton shales 

 at St. Paul. 



15. Portion of original of flg. 13, xg, illustrating the appearance of a large number of 

 specimens. 



18. A finely preserved fragment, natural size and a portion xg. in this specimen the 

 zooecla are unusually small. 



19 to 21. A very young specimen (var. minor of my preliminary report,) natural size, a por- 

 tion xg, and several zooecial apertures x35. The margins are wide and sharp, the 

 outer zooecial apertures large and oblique, and the walls in tl\,e central part very 

 delicately granulose. (See also plates VI and VIII.) 

 Middle third of the Trenton shales, Minneapolis and St. Paul, Minn. 



Figs. 16 and 17. Rhinidictya mutabilis, var. senilis, n. var 12 



A specimen of the natural size and a portion xg. 

 Middle third of the Trenton shales, St. Paul, Minn. 



Figs. 22, 23, 25 to 28, and 32. Ehinidictta maltabilis, var. major Ulr 12 



22 and 23. A well preserved but na.rrow stipe of this variety of the natural size, and a few 



zocecial apertures, with a portion of one of the solid spots or maculas, xi8. 

 25 to 28. Four specimens of the natural size. 



32. Small portion of the surface of the original of flg. 28, xg. (See also plate VI.) 

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



Figs. 24 and 29 to 31. Euktdictta multipoka (?Hall) 13 



24 and 30. A narrow, parallel-margined example of the natural size and a portion xg. This 

 resembles Bhinidictya mutabilis, var. major to such a degree that it was at flrst regarded 

 as belonging to that variety. 

 2g and 31. A small, irregularly divided frond, natural size and a portion xg. This spec- ' 

 imen is evidently young, being thin and but inconspicuously maculose. (See also 

 plates VI. and XIV.) 

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



