PLATE VIII a. 



I'll ICOPS CRISTAT v. 



See Plate t>. 



Fig. 1. Thorax and pygidium, drawn, fr a gutta percha impression of a natural mould of the doi-sal 



surface. The specimen is somewhat compressed laterally. 

 Pig. 2. Profile of the same, showing the elevation of the axial row of spines 



Schoharie grit. .1 'bany county. 

 Pig. '■<■ The under portion of the cephalon, showing the epistomal doublure and the crenulations of the 

 sub-frontal sulcus. 



Schoharie grit. K/mr, I ity. 



Pig. 4. An internal cast of the cephalon, enlarged one diameter; a portion of each cl k has I n broken 



:iwa\ i" show the sub-frontal crenulations. 



Schoharie grit. Clarisvilte, Albany county . 



PhaCops cristata, var. i'ipa. 



Page 18. 

 Pig. 5. Anentire, but somewhat crushed young individual, showing the proportions of this variety, and 

 ilif genal spines. 



(Villiferous limestone. LeRoy, Qenesei county. 

 Pig. 6. Front view of an internal east of a small cephalon, enlarged one diameter; showing the rotundit) 



of the glabella, the elevation of the occipital ring and the projection of the genal spines. 

 Fig. 7. Profile of the sane-, showing the protuberant glabella and the elevation of the genal spines. 



Upper Helderberg lin North Cayuga, Provina of Ontario. 



Fig. 8. The internal surface of the cephalon, enlarged one diameter. 



Corniferous limestone. FalU of tin Ohio. 

 Fig 9. An imperfect individual, retaining the cephalon and a portion of the thorax. 



Corniferous limestone. Canandaigua, Ontario county. 

 Fie-, in. A cephalon, drawn 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, ami the stout 

 -' iial spines. Enlarged one diameter. 



Upper Helderberg limestone. North Cayuga, Province of Ontario. 

 Pig. 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. W&lpole, Provina if Ontario. 

 1' 13. A small, imperfect cephalon, showing the glabellar furrows. 



Upper Helderberg limestone. North Cayuga, Provinei of Ontario. 

 Fig. 14. A. pygidium of. average size. 



Corniferous limestone. Liuu Rock, near LeRoy, Genesee county. 

 Fig. 15. A portion of a small pygidium, enlarged, to three diameters; showing the paired muscular 

 -ears, through the slightly weathered crust. 



Corniferous limestone. Canandaigua, Ontario county. 

 Fig. 16. A huge cephalon. preserved as a cast of the internal surface, and showing the genal spines. 



• Oriskany sandstone. Cayuga, Provina of Ontario. 

 Fig. 17. A pygidium, preserved as an internal east, and found in association with cephala similar to the 

 foregoing. 



Oriskany sandstone. Cayuga, Provina of Ontario. 

 This and the preceding Specimen are referred with some hesitation to this variety, and may more 

 properly lie regarded as examples of the species itself. 

 Fig. IS. An hypostoma, found in association with fragments of this variety ; enlarged to four diameters. 

 Corniferous limestone. Canandaigua, Ontario county. 



