PLATE XII. 



Page 



Figs. 1 to 4, 30 and 31. oEsohabopoba angtjlaeis, n. sp 161 



1 and 2. A small specimen of natural size and the greater portion of it xg. 

 3 and 4. A large specimen of tlie natural size and a portion of the upper half of its sur- 

 face X18. 

 30 and 31. Vertical and tangential sections, x 18. 

 Trenton limestone, Minneapolis. 



Figs. 5 to 29. ESCHAROPOBA SUBEBBCTA Ulr 16f 



5 to 17. A series of specimens, most of them above the average in size and the four last 



with from one to three rows of monticules. 

 18 and 19. The central and basal portions of the original of flg. 9, xg. 



20. Part of same, xi8. The characters as shown in this specimen are to be regarded as 



typical for the species in its younger stages. 



21. Surface of another small example, xi8, with the marginal rows of zooecia unusually 



conspicuous. 



22. Surface of the basal third of the original of flg. 15, xi8. The features here presented 



are unusual. 



23. Surface of the upper part of the original of flg. 16, xi8. 



24. Surface of the original of flg. 17, xi8. In the specimen the zooecial apertures manifest 



a tendency to arrange themselves in an obscurely pinnate manner. 



25. Tangential section of an example corresponding to flg. 9; xi8. 



26. Tangential section of a specimen of the size of flg. 8, or a trifle larger; xi8. 



27. Tangential section, xi8, showing the appearance just beneath the surface of an old 



example. 



28. Vertical section of several zooecia prepared from an average specimen, xi8. 



29. Transverse section of same xi2. 



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



