Plate L\\lrontimiet1. 



PAGE. 



Fig. 4. RHOMBOPOBA THANSVERSALIS Ulr C^4 



4. Fracment of the natural size, showing the transverpe furro vs as they 



appear in a fully matured example. 

 Keokuk group, Warsaw, 111. 

 Illinois State Museum. 

 4 a. Suiface of same, x]2. 



4 6. Tangential section, xis. 



Fig. 5. RHOMBOPOEA ? SPIRACIS Ulr G56 



5. A fragment of this species, natural size, with two portions of its surface 



x!2. The interspaces carry granules, which, when the surface is 

 abraded, are represented by small pores. 



5 a. Another fragment, x!2. This is abraded and has the zooecia apertures 



surrounded by one or two rows of small pores. 



5. Small portion of a tangential section, x!8, showing pores of various sizes 



in the walls. 



5 o. Transverse section, x!8, showing the spiral arrangement of the zooecia 

 about the center. 



5 d. Vertical section, x!8. Sections of this kind closely resemble those of 



Streblotryjia major. The species may have to be referred to that 



genus. 



Keokuk group, King's Mountain, Ky. 



E. O. Ulrich's collection. 



Fig. 6. BACTBOPOBA SIMPLEX Ulr. (See also PI. LXX.) 663 



6. Tangential section, x!8, showing the peculiar stellate character of the 



acanthopores. 



6 a. Small portion of a vertical section, x!8. 



Fig. 7. STBEBLOTBYP A SUBSPINOSA Ulr 668 



7. Two examples showing natural size and mode of branching. 



7 a. Surface of one, x!8. 



Chester group, Kaskaskia, 111. 

 Illinois State Museum. 



Fig. 8. STREBLOTBYPA MAJOB Ulr. (See also PI. LXXII.) 666 



8 and 8 a. Two fragments of the small form of this species. 



King's Mountain, Ky. 



E. O. Uliich's collection. 

 8 ft. Surface of fig. 8, xlg. 

 8 c. Portion of a tangential section, x!8. 

 8 d. Example of the large form, natural size. 



Keokuk group, Nauvoo, 111. 



Illinois State Museum. 



