PLATE XXVIII. 
Figs. land 2. SPATIOPORA LABECULOSA, Nl. SP, .....eee ee cess eect eee cece cette eet e eet e eee ence ene 
1. Surface, *9, of a specimen with macule of the usual size. Others may have smaller 
macule and more numerous mesopores between the zocecia. 
2. Tangential section of Same, <18. 
Middle third of the Trenton shales, Minneapolis, Minn. 
Figs. 3 to 7. CERAMOPHYLLA FRONDOSA, D. Zen. CUSP..-. 0. see cece cece ee cece t eet cece eee eee eee eee 331 
3. Nearly complete frond of this species, nat. size. 
4. Small portion of its surface, x9, showing in the lower left hand corner the greater part 
of one of the maculz. 
5and6. Small parts of two tangential sections, 18, the former illustrating the normal 
development, the latter an old and more irregular arrangement, and greater width 
of interspaces due to proximity to a macula. 
7. Half of a vertical section, X18; the tubes are divided somewhat obliquely and therefore do 
not show the full length of the prostrate portion. 
Upper third of the Trenton shales, St. Paul, Minn. 
Figs. 8 to 11. CERAMOPORELLA INCLUSA, D. SP... - 0-00.00 eee eee e cece eee eee eee es cence eee 329 
8. Surface, 9, of an example having the apertures filled with the clayey matrix. 
9. Small portion of another example, *18. 
10. Larger part of the surface of the original of fig. 9, <9. 
11, Selected normally developed zocecium, 40, 
Lower and middle thirds of the Trenton shales, Minneapolis, Minn. 
Fig. 12. IG DRAMOPOREETALIN TERE O ROSAS ail cs P)elerlalstelaretaleteretsetelet Voie ohavatetoteletetefcteletete fol ttetelcle ese inis)-jatcaraitets 330 
Surface of an average specimen of this species *18. 
Galena Shales near Cannon Falls, Minn. 
Fig. 13. CERAMOPORELLA DISTINCTA, LOE cpl Sonat ne ees te Sere ae a et Lis eS - 3828 
Surface of a small specimen of this species from the lower third of the Trenton shales 
at Minneapolis; *18. 
Fig. 14. DIAMESOPORA TRENTONENSIS, 1. SP... . 0. - esses ce ee eee cence eee teen cece eee cence ent e eee 330 
Two specimens of the natural size and the surface of the upper x9. The form and ar- 
rangement of the zocecia js a little irregular in this specimen. In others their shape 
approximates fig. 11. 
Galena shales near Cannon Falls, Minn. : 
Figs. 15 to 20. .ANOLOTICHIA IMPOLITA UIP... -...-.. 1. eee ee eee cece teen ee cee nee teens 327 
15 and 16. Surface x9 and x18. 
17. From the axial region of a transverse section *18. 
18. Small portion of a tangential section X18, of a specimen in which many of the lunaria 
have only two tubuli. 
19. Portion of a typical section X18. 
20. Vertical section <9. 
Lower third of the Trenton shales, St. Paul and Minneapolis. 
Figs. 21 t0 25. ByQTHOTKYPA LAXATA Ulr.................... Gosbasdnonudsduuonaadoppasapae DSO bAGIO 325 
21 and 22. Surface of a well preserved specimen <9 and *18. 
23 and 24. Vertical and tangential sections x9. 
25. Portion of the tangential section <18. 
Trenton shales, Minneapolis and St. Paul. 
Figs. 26 to 28. CREPIPORA SUBHIQUATA, ND. SP... see cece cece eee cece cece eee teen e en cee e eee eenes 322 
26 and 27. Tangential section x9 and X18. ; 
28. Vertical section <9, the entire thickness of the zoarium being shown in the right half 
of the figure. 
Upper third of the Trenton shales, St. Paul. 
Figs. 29 to 82. CREPIPORA PERAMPLA, D. SP....--eeseee eee sence een e eter teen cence ec eee tees ne ees 323 
29 and 30. Vertical and tangential sections <9, the latter with the lunaria unusually distinct. 
31. Portion of the tangential section <18. 
32. Another tangential section <9, with the lunaria scarcely distinguishable. 
Top of the Trenton limestone, Fillmore county, Minn. 
