PLATE XX. 



PAGE. 



Figs. 1 to 9, 13 and 14. MONTICULIPOKA ABBOUEA, n. sp 220 



1. Peripheral part of a vertical section xis. 



2. Several tubes from the axial region of same xis, showing the presence of cystiphragms in 



even this portion of the zoarium. 



3. Transverse section from the center to the periphery of a branch xis, proving the presence 



of cystiphragms throughout. 

 4 and 5. Fully matured portion of a tangential section xis and a small part of same X50. 



6. Shows the appearance at a slightly lower level than flg. 4. 



7. Small portion of the surface of the specimen represented by flg. 8; xg. 



8 and 9. Two fragments of the natural size exhibiting a difference in the prominence of 



the monticules. 



Galena shales near Cannon Falls, Minn. 

 13 and 14. Tangential and vertical sections of a form of the species from the Trenton at 



Burgin, Ky.; xis. 



FigS. 10 to 12. MONTTCULIPORA (?) CANNONENSIS, n. Sp 221 



10 and 11. Vertical and tangential sections xis. 

 12. One zooecium X50. 



Galena shales near Cannon Falls, Minn. 



Figs. 15 to 21. HOMOTRYPA CALLOSA, n. sp 243 



15 and 16. Tangential sectionxis and a small portion of same xso, of a specimen from the 

 Galena shales near Cannon Falls. 



17. Vertical section of same xis. 



18 and 19. Peripheral and axial portions of a vertical section xis, prepared from a specimen 

 from the Trenton at Burgin, Ky. 



20 and 21. Tangential section of same xis and X50, differing slightly from that of the Min- 

 nesota form. 



Figs. 22 to 27. ATACTOPORELLA RAMOSA, n. sp 226 



22. Two portions of a tangential section xis, exhibiting differences that depend upon the 



varying depth at which the section passes through the zoarium. 



23. Small portion of same more highly magnified. 



24. Axial region of a transverse section xis. 



25. Vertical section xis, showing the continuance of the series of cystiphragms into the 



axial region. 

 26 and 27. Two specimens of the natural size. 



Upper third of the Trenton shales near Cannon Falls, Minn. 



Figs 28 to 33. HOMOTRYPA SIMILIS Foord* 242 



28. Portion of the peripheral third of a transverse section xis, Cannon Falls. 



29. Vertical section of an authentic Canadian example of the species x!8. 



30. Two portions of a tangential section of same xi8. 



31 and 32. Vertical and tangential sections of a Minnesota specimen, xis. 

 33. Surface of another specimen from this state xis. 



Trenton limestone Ottawa, Can., and upper part of the Galena shales near Cannon 

 Falls, Minn. 



*The systematic position of this species Is doubtful. Though falling In a loose way under llomotrypa some of Its char- 

 acters are so peculiar that It can in no wise be regarded as a true representative of the genus. Thin sections are suggest- 

 1 vely like those of Homotrypella instabttis and in some features also simulate those of Eridotrypa mutaliili*. 



