PLATE XXI—Continued. 
Proetus MACROCEPHALUS. 
Page 116. 
See Plate 23. 
Fig-. 10 An obliquely crushed individual, i-etaining the right eye and fixed cheek. 
Hamilton group. Canandaigua Lake. 
Fig. 11. A large imperfect individual. 
Hamilton grouii. Jaycox'a Run, nea.r Geneseo, Livingston cotmiy. 
Fig. 12 An imperfect specimen, wanting the free cheeks as is usual. 
Hamilton group. Cayuga Lake. 
Fig. 13. A jioi-tion of the cephalon, showing, by compression, the glabellar furrows. 
Hamilton group. York, Livingston county. 
Fig. 14. An entii-e cephalon, also showing- some of the glabellar furrows. 
Hamilton group. Canandaigua Lake. 
Fig. 15. The pygidiuin of a small individual, enlarged to two diameters. 
Hamilton group. Near Geneseo, Livingston county. 
Fig. 16. A pygidium from the limestone, similarly enlarged. 
Hamilton group. Eighteen-mile Creek, Eh-ie county. 
Fig. 17. A pygidium, showing the intei-nal sni-face and the doublure. 
Hamilton group. Canandaigua Lake. 
Fig. 18. A pygidium enlargeil to two diameters, showing the axial nodes which give the annulations the 
appearance of being medially angulated. 
Hamilton gi-oup. Locality f 
Fig. 19. A lai-ge pygidium. 
Hamilton group. North Bristol, Ontario county. 
Fig. 20. Profile view of the pygidium represented in fig. 15. 
Fig. 21. Pi-ofile view of the pygidium represented in fig. 16. 
Proetus occidens. 
Rage 130. 
Fig. 22. A small pygidiuin retaining the crust, but not in such condition as to show the annulations with 
distinctness. 
Hamilton group ? New Buffalo, lotoa. 
Fig. 23. A large imperfect specimen. 
Hamilton group ? New Buffalo, loioa. 
Proetus Conradi. 
Page 89. 
See Plates 20 and 22. 
Fhg. 27. Anterior view of an enrolled, somewhat imperfect individual, showing the proportions of the 
glabella and the wide, sloping border. 
Fig. 28. Posterior view of the same. The axis of the body is made to appear too broad and stout. 
Schoharie grit. Schoharie, Schoharie county. 
Cyphaspis l^vis. 
Page 150. 
Fig. 29. The cephalon enlarged to twelve diameters. 
Chemung group. Chemung county. 
