PLATE XX. 



Page 



Figs. 1 to 9, 13 and 14. Monticulipora aeboeea, n. sp 22 



1. Peripheral part of a vertical section xi8. 



2. Several tubes from the axial region of same xi8, showing the presence of cystiphragms in 



even this portion of the zoarium. 



3. Transverse section from the center to the periphery of a branch xi8, proving the presence 



of cystiphragms throughout. 

 4 and 5. Fully matured portion of a tangential section xi8 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.; xi8. 



Figs. 10 to 12. MONTICULIPOBA (?) CANXONENSIS, n. sp 22] 



10 and 11. Vertical and tangential sections xis. 

 12. One zooecium X50. 



Galena shales near Cannon Falls, Minn. 



Figs.l5to21. HoMOTRYPA CALLOSA, n. sp 24; 



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

 Galena shales near Cannon Falls. 



17. Yertical section of same xi8. 



18 and 19. Peripheral and axial portions of a vertical section xi8, prepared from a specimen 

 from the Trenton at Burgin, Ky. 



20 and 21. Tangential section of same xi8 and X50, differing slightly from that of the Min- 

 nesota form. 



Figs. 22 to 27. Atactopokblla ramosa, n.sp 22f 



22. Two portions of a tangential section xi8, 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 xi8. 



25. Vertical section xi8, 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. HoMOTRTPA SIMILIS Foord* , 24! 



28. Portion of the peripheral third of a transverse section xi8, Cannon Falls. 



29. Vertical section of an authentic Canadian example of the species xl8. 



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 xi8. 



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



Falls, Minn. 



*The systematic position of this species Is doubtf al. Though falling In a loose way under Homotrypa some of Its ohai 

 aoters are so peculiar thatitcaa in no wise be regarded as a true represeutati\re of the genus. Thin sections are suggest 

 i vely like those otHomotrypeUa instabills and in some features also simulate those of Eridotrypa mutaibHis. 



