PLATE VIII A. 
Phacops cristata. 
See Plate 6. 
Fig. 1. Thorax and pygidium, drawn from a gutta-percha impression of a natural mould of the doiral 
surface. The specimen is somewhat compressed laterally. 
Fig. 2. Profile of the same, showing the elevation of the axial row of spines. 
Schoharie grit. Albany county. 
Fig. 3. The imder portion of the cephalon, showing the epistomal doublui-e and the crenulations of the 
sub-frontal sulcus. 
Schoharie grit. Knox, Albany county. 
Fig. 4. An internal cast of the cephalon, enlarged one diameter ; a portion of each cheek has been bi'oken 
away to show the sub-frontal crenulations. 
Schohai-ie grit. Clarksville, Albany county. 
Phacops cristata, var. pipa. 
Page 18. 
Fig. 5. An entire, but somewhat crushed young individual, showing the proportions of this variety, and 
the genal siiines. 
Cornifei-ous limestone. LeRoy, Genesee county. 
Fig. 6. Front view of an internal cast of a small cephalon, enlarged one diameter; showing the rotundity 
of the glabella, the elevation of the occipital ring and the projection of the genal spines. 
Fig. 7. Profile of the same, showing the pi-otuberant glabella and the elevation of the genal si)ines. 
Upper Heldei-bei-g limestone. JVo-rth Cayuga, Province of Ontario. 
Fig. 8. The internaj surface of the cephalon, enlai’ged one diameter. 
Corniferous limestone. Falls of the Ohio. 
Fig. 9. An imperfect individual, retaining the cephalon and a portion of the thorax. 
Corniferous limestone. Canandaigua, Ontario county. 
Fig. 10. A cephalon, di'awn from a gutta-percha impression of the dorsal surface, and slightly restored on 
one side ; showing the glabellar furrows, the broad and deep occipital furrow, and the stout 
genal spines. Enlarged one diameter. 
Uppej- Helderberg limestone. North Cayuga, Province of Ontano. 
Fig. 11. A large and characteristic pygidium, drawn from a gutta-percha impression of a natural mould of 
the dorsal surface. 
Fig. 12. The internal surface of the same specimen, showing the simple pleural annulations corresponding 
to the duplicate ribs of the upper surface. 
Upper Helderberg limestone. Walpole, Province of Ojitario. 
Fig. 13. A small, imperfect cephalon, showing the glabellar furrows. 
Upper Helderberg limestone. North Cayuga, Province of Ontario. 
Fig. 14. A pygidium of average size. , 
Corniferous limestone. Lime Rock, near LeRoy, Genesee county. 
Fig. 15. A portion of a small pygidium, enlarged, to thi'ee diameters; showing the paired muscular 
scars, through the slightly weathered crust. 
Corniferous limestone. Canandaigua, Ontario county. 
Fig. 16. A large cephalon, preserved as a cast of the internal surface, and showing the genal sxiines. 
Oriskany sandstone. Cayuga, Province of Ontario. 
Fig. 17. A pygidium, preseiwed as an internal cast, and found in association with cephala similar to the 
foregoing. 
Oriskany sandstone. Cayuga, Province of Ontario. 
This and the preceding specimen are referred with some hesitation to this variety, and may more 
properly be i-egarded as examples of the siiecies itself. 
Fig. 18. An hypostoma, found in association with fi-agments of this variety ; enlarged to four diameters. 
Corniferous limestone. Canandaigua, Ontario county. 
