Fig. 



1. 



1. 



Fig. 



2. 



Fig. 



3. 



3. 



Fig. 



4. 

 4. 



Fig. 



5. 



5. 



Fig. 



6. 



6. 



Fig. 



7. 



PLATE XXVII. 



PAGE. 



AcidaspiS Ortoni Foerste 522 



A head B. O. 



Proetus determinate Foerste 523 



A glabella with part of anterior border ; same as figure 5 of plate XXVI. S. H. O. 



Prcetus determinatus Foerste 523 



A glabella, S. H. O. 



Phacops trisulcatus Hall 529 



Probably a pygidum of this species S. H. O. 



Cyphaspis Clintonensis Foerste 524 



Glabella. B O. 



Ill-Enus dayTonensis Had and Whitfield .- 525 



A rostrum in position. B. O. Collection of Prof. W. S. Hoskinson. 



Ill^Enus madisonianus Whitfield 526 



7. Glabella. B. O. 



Fig. 8. Ill^Enus madisonianus Whitfield 526 



8. Pygidium ; moderate^- elongated. B. O 

 Ill^Enus madisonianus Whitfield 526 



Pygidium, very slightly elongated. B O. 



Ill-Enus madisonianus Whitfield 526 



Pygidium not at all elongated, all these specimens are only very small forms of 

 the species. 



Ill.Enus daytonensis Hall and Whitfield 525 



Movable cheek, Ludlow Falls, O. 



LlCHAS 



Hypostoma, differing considerably from that of L breviceps, and possibly belong- 

 ing to a poorly preserved apparently distinct form, described in the text as 

 Lichas phlyc ainoides 



Calymene vogdesi Foerste 526 



Head, same as figure 25 of plate XXV C. O. 



Calymene vogdesi Foerste 526 



Outline of the preceding head. C. O. 



Calymene vogdesi Foerste 526 



Part of head, same as figure 2-1 of plate XXV, reconstructed from fragments. 

 S. II. O. In ihe middle limes-tones 



Calymene vogdesi Foerste 526 



Outline of the preceding head. S. H. O. 



Calymene vogdesi Foerste 526 



A characteristic pygidium, associated with forms like those shown in figure 12 

 and 13. C O. 



Ceraurus (pseudosph^rexochus) clintonensis Foerste 527 



A Glabella. B. O. 



Lichas breviceps Hall 529 



Of the form with a veiy distinct lobe towards either end of the occipital furrow, 

 a characteristic of the Clinton specimens, hence called variety Clintonexsis. 

 B O. 



Lichas breviceps Hall.... 529 



Hypostoma. B. O. 



Phacops trisulcatus Hall 529 



Part of head, same as figure 3 plate XXVI, B. O. 



Phacops trisulcatus Hall 529 



Head, a more perfect specimen. S. H. O. 



Fig. 



9. 





9. 



Fig. 



10. 





10. 



Fig. 



l(k 





Via. 



Fig. 



11. 





11. 



Fig. 



12. 





12. 



Fig. 



13. 





13. 



Fig. 



14. 





11. 



Fig. 



15. 





15. 



Fig. 



16. 





16. 



Fig. 



17. 





17. 



Fig. 



18. 





18. 



Fig. 



19. 





19. 



Fig. 



29. 





20. 



Fig. 



21. 





21. 



