Plate LXX Continued. 



Fig. 13. RHOMBOPOKA DICHOTOMY Ulr 



13. Nearly entire example; natural size. 



Burlington limestone, Burlington, Iowa. 

 Illinois State Museum. 



13 a. Portion of surface just beneath the first bifurcation, x!2. 

 13 6. Portion of surface between the third and fourth bifurcations x!2. 



I'ACiK. 



.. 650 



Fig. 14. BACTBOPOBA SIMPLEX Ulr. (See also PL LXXI) 



14. Two complete examples, natural size. 



Keokuk Group, Warsaw, 111. 



E. 0. Ulrich's collection. 

 14 a. Small slab with a number of specimens; natural size. 



Keokuk g^oup, Nauvoo. Ill 



E. O. Ulrich's collejtion. 

 14 b. Surface of well preserved example, x!2. 



