PLATE XX—Cou tinned. 
Fig. 
Fig. 
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Fig. 
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Fig. 
Fig. 
Fig. 
Fig. 
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Fig. 
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Fig. 
Cyphaspis minuscula. 
Page 140. 
See Plate 24. 
17. An entire individual, enlarged to three diameters. The outline of the pygidium is incorrectly 
represented, and through an ovei'sight has been left untinted. The cheek spines are also 
made to appear shorter than in the specimen. 
Corniferous limestone. SchoJiane, Schoharie county. 
Pkoetus Verneuili. 
Page 108. 
18. The original specimen, showing a portion of the thorax, the pygidium, and the chai-acteristic 
nodes on the pygidial border. Enlarged to thi-ee diameters. 
19. Profile view of the same. 
Upper Helderberg limestone. WiUiamsmlle, Erie county. 
Proetus crassimarginatus. 
Page 99. 
See Plates 22 and 25. 
6. The pygidium as a cast of the internal surface, showing the doublure and the obscure annulations. 
This usual condition of preservation in the Schoharie grit. 
Schoharie grit. Near Clarksville, Albany county. 
7. P)-ofile view of a lai-ger pygidium, an inteimal cast, upon which the annulations are obsolete. 
8. Dorsal view of the same. 
Schoharie grit. Albany county. 
20. An imperfect glabella with the crust nearly all removed. 
21. Profile view of the same. 
Corniferous limestone. Falls of the Ohio. 
22. A very large glabella. 
Upper Helderberg limestone. Near Clarence, Erie county. 
23. The left free cheek. 
24. Lateral view of the same. 
Upper Helderberg limestone. Near Clarence, Erie county. 
25. A small pygidium. 
Corniferous limestone. Falls of the Ohio. 
26. A larg-er pygidium, showing the charactenstic curves of the axial annulations. 
Corniferous limestone. Falls of the Ohio. 
27. A large pygidium. The drawing fails to represent the proper degree of rotundity. 
Upper Helderberg limestone. - Cayuga, Province of Ontario. 
28 (23 in erroi'). A large, elongate pygidium. 
Upper Heldei’berg limestone. Williamsvhlle, Erie county. 
29. An unusually large pygidium. 
Upper Helderberg limestone. Williamsville, Erie county. 
30. Profile view of the pygidium represented in tig. 28. 
31. Profile view of the pygidium represented in fig. 29. 
Proetus (?) longicaudus. 
Page 131. 
32. Anterior aspect of the type specimen. 
33. Profile view of the same. 
42. Posterior aspect of the same. 
Hamilton group ? Locality doubtful; from some point north-ea.st of Des Moines, Iowa. 
[Probably of Lower Carboniferous age.] 
